Using FPC to Size Truck and Loader
Fleets
©2012 Dr. B. C. Paul
Note – This presentation demonstrates fleet sizing using Caterpillar’s FPC program
and includes screen shots from the program. Credit is given to Caterpillar for the
program and interfaces. Caterpillar has produced helps and directions for using the
program which of course have common subject material with these slides. These
slides also draw on earlier work done by the author.
What Is FPC?
• It is an easy to use tool for sizing truck and
loader fleets for hauling ore over simple and
consistent haulage routes
What Will We Do In This
Demonstration?
• We will consider a fleet of trucks moving
16.5 million metric tonnes of rock every
year out of a pit that is 500 meters deep.
• Similar to the final pit we developed in
MineSight.
When FPC Starts it Takes You to Its
First Tabbed Screen
Some Items Just Involve
Labeling Your Project
You Also Make Your Unit Selection
You Need to Enter A Fuel Price
Normally the fuel is “Red Dog”
Diesel.
Most Trucks run on Diesel Fuel
Most Mining Trucks do not run
On public highways. As a result
Their diesel fuel is not subject
To highway taxes.
To keep untaxed diesel fuel from
“getting into the highway truck
Fleet” it is dyed red. Thus the
Name “Red Dog”. If a highway
Truck is cought with red fuel or
Red fuel stains there will be big
Trouble.
Working Time is Also Considered
You enter the number of hours
Per year of work
And the so called shift efficiency
Hours Worked
• One Begins Considering How Many Hours to
Schedule Mining Operations and trucks.
• You could claim 24 hours a day and 365 days per year
• But that would imply Christmas, New Years, and other
Holidays being worked
• That would also imply no weather delays or scheduled
maintenance down-town
• It would mean no weekends off
• It would mean if you ever got in trouble on production there
would be no place to add time for catch-up
• Not Surprisingly – 24 hours/day 365 days per year is
not a usual choice
Some Possibilities
• 5 days per week
• 52 weeks per year – about 260 days/year
• A month off for Miners Holiday
• Mines shut down and use crews for heavy maintenance
and prep work
• Leaves around 330 days with a few major holidays
• 6 day work week – 52 weeks/year – about 312
Weather or Not You Like It
• Consider how many days you may loose for
weather or catastrophic break-down events
• For my example I selected 325 days/year
• I was going for a 7 day per week operation with
reasonable holiday, maintenance, and weather
or break-down days.
• Be consistent with existing or intended
practice.
The Shifts/Day Issue
• In theory three 8 hour shifts make 24 hours per day.
• In practice changing crews takes time
• Idea behind “hot seat change outs” start the next shift before
previous ends
• Of course that will end the idea that three 8 hour shifts = 24 hours
• Some mines use 2 work shifts and a maintenance shift
• If they are 8 hour shifts you might get 14 or 15 hours – not 16 with
hot seat change outs
• Some mines use 10 hour shifts
• Works with 4 days on and 3 off schedules – may not be
accommodating to workers with fixed weekend needs (Saturday or
Sunday Church for example)
• Can probably get 18 or 19 hours
• Often run two 10 hour work shifts with a 8 hour maintenance
More Shift Issues
• Day-Light hours
• Lower 48 U.S. usually have around 10 or better of
some type of daylight
• Not an issue if you have an artificial light grid
• Counting on running massive haul trucks off of “head-lights”
is not likely or safe
• Do you have an artificial light system?
• If your planning the mine is that light system in your cost
projections?
• Many quarries lack artificial light so 10 hour days is
almost forced on them
• If you are in the Arctic Circle you have whole months
with no light
My Assumption
• 21 hours per day
• It’s a three 8 hour shift schedule without hot
seat change outs and planned non-utilized time.
• Often your days per year and hours per day
decisions are not independent of each other
The Shift Efficiency Issue
• Reality is you never get 100% work time to match a
schedule
• First factor is “Available”
• The fact that I planned on using something does not guarantee it
will be running
• Second factor is “Utilized of Available”
• There are scheduling complexities – you seldom use something
just because its running
• Third factor is “Shift Efficiency”
• Workers are required by law and biology to have breaks in an 8 or
10 hour period
• Typically you get about 50 minutes out of every hour – about 8384%
Cat FPC
• Cat FPC has “shift efficiency”
• I put in 83%
• The program builds “shift efficiency into every shift”
• Don’t use this to cover planning related non-utilization when
equipment is available – non-use is seldom evenly spread
across every shift
• Legal and biological breaks are distributed across and shift
which is what FPC assumes
• FPC will use shift efficiency to make sure your tires
don’t overheat
• If you use “shift efficiency” to cover unevenly spaced
scheduling difficulties you may blow-out tires in the field
when you try to implement the plan
More on FPC
• Although We Have not Seen it Yet FPC allows
you to identify percentage available
• Ie – allow for what % of the time the equipment is in
running order
• Note FPC does not have “Utilized of Available”
• You have to build that into your working hours per year
entry (which I tried to do by scheduling 21 hours per
day for three 8 hour shifts)
The Last Issues are Bunching and
Operator Efficiency
What Is Bunching?
• If you have 5 trucks and one loader in theory the
loader always has a truck available and when-ever
a truck arrives the previous truck is just pulling
away.
• But this requires perfect spacing between trucks
• Drivers tend to congregate, three trucks may arrive to
be loaded and have to wait
• Then the loader has all the trucks away and nothing to load
into
• This is called Bunching
• It reduces the theoretically possible production
FPC and Bunching
• Cat did extensive studies on production losses
from bunching
• It is one of the few programs to build bunching losses
into predicted Production.
• I picked average (which means to use the Cat
typical statistics)
• I could pick “none” and not using bunching losses at all
(but they will likely happen anyway)
• I could pick “min”
• I could pick “max” – more typical of what would
happen if the road was congested and did not allow
passing
Operator Efficiency
• The Truck speed is limited by its own engine size
and drive train limits
• Or by road imposed speed limits
• Trucks usually don’t travel at the maximum
possible speed
• Cat has compiled statistics on the ratio and found it to
be a function of distance.
• I picked the button to use the Cat empirical study
• I could alternately choose a fixed percentage of the
ratio of my average speed to the theoretical maximum
speed.
Note!
• There are 4 quick to enter numbers on the
first panel that have huge policy and
practice implications
• Fill those numbers out with a full
understanding of what you are planning
• Don’t just blow them off and expect to get good
results.
FPC is Set Up By Moving Directly
Across the Tabs at the Top
Now we go to Fleet Input
You Can Try Different Fleets of
Trucks
Each fleet has a name you give it – and a description you or your team use to keep
Straight what you are doing.
Now Start Building Your Fleet –
Click Add Hauler
The Select Hauler Window Opens
I wanted a Cat Standard Machine
(others require user input)
I wanted a Truck
(When I select this the blue list
Below opens)
And obviously for my Cat 793
Fleet I wanted a Cat 793.
A Bunch of Truck Specific Default
Data Comes Up
Note that this is where I get access
To the working availability time
Of the truck unit.
Availability Considerations
• Newer trucks tend to have higher availability
• 90 to 95%
• Some people “rent fleets and simply pay a cost per ton
– Cat maintains and usually guarantees around 95%
availability
• Old highly worn trucks tend to drop down to about
60%
• 85% is usually regarded as an old middle of the
road average standby
• In a more complex run I could change the value as
my fleet aged.
I’m Using an old 85% Middle of the
Road
I will now move on
And select my loader.
Interesting note – I am
Holding out on inputting
My number of trucks
And cost data till I get
An idea of how many
I need.
On the Select Loader Panel
I will again pick Cat
Standard Machines
I’m going to try a Cable
Shovel first
It brings up the P+H line
At this point we need a
Discussion on matching
Trucks and shovels.
The Loader and Truck Need to Be A
Match
• The Loader Should be able to fill the truck
in a reasonable number of passes
• The Loader Should be able to lift the load
up over the side of the truck and dump the
material in.
• At this point we better have our Cat
Handbook handy.
Need to Fill in a Reasonable Number
of Passes
• If you fill a truck with less than 3 passes you can’t get the
load distributed – you’ll kill the suspension system in the
truck
• If you take too many passes to fill the truck will spend a
large part of its cycle time sitting to be loaded.
• Guidelines exist as to what tends to be workable
•
•
•
•
Cable Shovels (3 to 4 passes)
Hydraulic Shovels (4 or 5 passes)
FEL (4 to 6 passes)
Backhoes (often 5 to 7 passes)
• Looks like we’ll be shooting around 3 or 4 passes.
But How Much Will The Truck
Hold?
• A Truck can be Weight or Volume Limited
• Which depends on the material
• Our Cat 793 holds 169 cubic yards just in
the bed, but 230 cubic yards if you heap it
and it can carry 250 tons.
Material Weights Tables Exist in
Many Handbooks
This one is from the Caterpillar
Performance Handbook
Porphyry Copper ore is GraniteLike
2800 lbs/cubic yard loose
4600 lbs/cubic yard bank
With a “load factor” of 0.61
A Material Caution
• In place rock is a solid with only internal air
spaces and pores
• For loading and hauling rock tends to break
into chunks that have air spaces between
them
• If you’ve ever tried to put dirt back in a hole
after digging it out you know what “Swell”
means
Always Distinguish Between Bank
and Loose Volume
The difference between bank and loose weight is huge
Saw some students foul up homework by looking on the internet
And grabbing a weight number with no idea what it was. Many
Internet numbers are bank weights since loose weights are often
Important only in mine planning.
In Our Case We Are Given the
Loose Weight
• 2800 lbs per cubic yard
• 169 cubic yards * 2800 lbs/yd^3 / 2000 lbs/ton
• 237 tons
• Rated weight for truck is 250
• Because this truck hit the volume limit before the
weight it is called Volume limited
• I bet you can guess what would happen if we were
weight limited
• We’ll we don’t have to – if we heap it a little we
can get up to 230 cubic yards
Continuing Our Calculation
• 230 * 2800 / 2000 = 322 tons > 250 tons
• Reality is that this truck is weight limited
• We can slightly over or underfill a truck
• Less than 95% of rated weight usually wasting
truck carrying capacity
• More than 105% of rated weight and you’ll tear
up the suspension
• Usually a good idea to aim for the middle and
allow the play for iregularities in loading
More Calculations on the Side
• 250 tons *2000 /2800 lbs/cubic yard
• I need about 179 cubic yards to fill
• Now my loader needs to do this in an
integer number of passes
• 3.5 passes is not a real number, I can only dump
dippers of material in integer amounts
How Much Can a Bucket or Dipper
Hold?
• That depends on the material its digging
• And on the degree of control the operator
has for the bucket through the dig path
• A Bucket or Dipper has a manufacture rated
capacity based on the volume of the Bucket
• But filling up all that space exactly is a trick
• We have “Fill Factors” that give the percentage
of the capacity that actually gets used.
By Material and Machine Type
• The Hydraulic shovel can pivot its bucket in most
of the ways you can pivot your hand – helps get a
good fill
• It has the best fill factors
• Loose material out of stock-pile 100 to 110% (also written 1 to
1.1)
• You do need an unusual material stacking angle to get over
100% (the bucket is already rated heaped)
• Average well-blasted bank 0.95 to 1
• Hard digging 0.9 to .95
• Very hard digging – blocky and poorly blasted 0.85 to .9
Moving Down the List
• Cable Shovels come in next – the dipper pushes
through on the end of a rigid arm
• But the Bucket is rated on struck capacity – not heaped.
• Loose Stockpile Like Materials
• Sand and Gravel 0.95 to 1
• An unconsolidated face with a few boulders 0.9 to 0.95
• Well Blasted Rock – called Hard digging for a Cable
Shovel – 0.8 to 0.9
• Poor Blasted with interlocking large blocks – called
very hard digging 0.7 to 0.8
Our Worst
• The Front End Loader
• It has little pivot and a bucket as wide as the machine
• It has to use its drive system to try and ram into what it digs
• Stockpiles
• Uniform moist or sand-like 0.95 to 1
• ¼ inch uniform pee gravel 0.9 to 0.95
• Larger sizes 0.85 to 0.9
•
•
•
•
Well blasted face – easy to dig 0.8 to 0.95
Average blasted rock face – 0.75 to 0.9
Poor blasting – 0.6 to 0.75
Very hard digging - won’t go through at all
• Of course operator ability can play any of these numbers
toward the top or bottom of the range
Consider a Cable Shovel Match for
Our Truck
• A 4100 has a 56 yard bucket
•
•
•
•
•
Average blasted face about 0.85 fill (0.8 to 0.9)
Target is 179 cubic yards
3 passes – 143 cubic yards
4 passes – 190 cubic yards
We are between
• If we got 0.9 fill 3 passes would hit 151 cubic yard
• It will be 4 passes
• 179 / 4 = 44.75 cubic yards
• 44.75 / 56 = 0.8 well within range for our expected digging
• Note at the very end the fill factor must match a loaded
truck with an integer number of dipper passes
Considering Other Shovel Sizes
• I had thought about a 2800XP but I’m
already at 4 passes with a 56 cubic yard
bucket so a 39 yard not a good candidate
• I had also thought of the really big 5700XP
with a 70 yard bucket
• 70*3*.85 = 179 cubic yards
• I can do a 4100 with 4 passes
• Or a 5700 with 3 passes
I Picked the Midsize 4100
If I wanted to try
More than one
Fleet I could
Select Add New
Fleet and then
Pick my 793
Matched to a 5700
Now I Need to Deal with
Availability
• Cable Shovels today use modular solid state
electronics
• Boards can be swapped out fast and sent for rebuild
• Structural design of Cable Shovel is Simple
• Does not have a lot of dirt sensitive highly stressed
hydrualics
• 90 to 95% availability should be fairly easy
• (old units with motor generator sets more like 80 to
85%)
Remaining Panel Issues
Does your haul
Road allow trucks
To pass?
(This is highly
Related to your
Mines traffic
Control plan)
I’m deliberately
Bypassing the
Exact number
Of trucks or
Loaders and
Their cost.
I could include support equipment for this fleet within
FPC or deal with it somewhere else – don’t miss it in your plan
Why am I bypassing?
• FPC is designed with the intent you put the cost of
your equipment in now
• It also is designed with the idea that you guess a
number of units
• Personal Style
• I like to go quick and dirty and get routines to tell me
about what number of units to try
• Then I’ll make a second pass with more detail
• FPC will work for a first pass rough size – and that is
what I like to do. (You may be different)
What is This Support Equipment
Issue?
• Trucks 250 ton and up are called Super Trucks
• They are very productive and have longer lives than an
average truck
• They also depend on a solid haul-road
• That means you are doing sub-bases and almost designing the
haul roads like highways
• Means for road work I have dozers and road
graders and probably a compactor
• Dirt roads probably mean I have water trucks both
for environmental reasons and also to moisted
road base for maximum compaction
Other Support
• Cable and Hydraulic Shovels are messy creatures
• They spill part of their rock
• Some sort of front end loader or scoop is used to collect
spills
• If the loader is large enough it loads into trucks
• If you allow rock to build up in your loading area
it will cut your truck tires
• There are about 40,000 + good reasons to not want that
to happen ($$$$)
Decisions about Support Equipment
in FPC
• I generally do not do my support equipment in FPC
• My road requirements are a function of my road length and
how often I have to relocate roads
• These functions are more associated with my mine plan than the
number of trucks in my fleet
• My clean-up loader is sensitive to the position of my
loading points and where else in the mine I may use them.
• I keep them out of FPC because I find their specifications
tend not to correlate well with exactly what I’m doing with
my trucks and loaders.
When I Try to Move On I Get a
Hysterical Message
My loader and truck
Costs are zero.
FPC really likes me to
Enter now – but I’m
A rough first pass
Designer
I’ll tell it Ok and move
On.
What’s Under Those Subtabs
It’s the rimpull and
Retarder curves for
The truck.
(If I did not pick
Cat standard I would
Get to enter this stuff
Myself)
On to the
rd
3
Tab
In this tab I will describe the road that my trucks must travel to deliver their ore or waste
Loads.
Name the Course and the Amount of
Material
I’m going to consider the route
For ore to the mill.
I know from some things in the
Next unit that I will be moving
Around 9,000,000 tons of ore.
Input My Information
If I already know my material loose
And bulk density I can enter it
Direct. Or I can click select material
To use Caterpillar’s built in data
Base.
On the Material Window
I select broken
Granite as most
Similar to porphyry
Copper ore.
Once I have selected
Granite Ok becomes
Available to click.
Now I Need to Describe My
Haulage Route
I will need to identify the length of the segment, the grade resistance,
A rolling resistance, a speed limit (if needed), and a description (which
Comes in very handy during later review)
How do I Divide a Continuous Road
into Segment?
• Road Segments Divide When
• There is a major change in grade (slope)
• There is a major change in underfoot conditions
• There is a major change in vehicle operating
considerations
• Starting
• Stopping
• Major Turns
What is Major?
• Depends in part on what you are doing
• Computer Methods favor greater detail
• Hand methods favor more moderation
• Good intuitive Check is whether sustained
enough to change vehicle speed
My Haulage Profile
• My loading bench is level and I will go 550
feet to the ramp to get out of the pit.
• Issue #1 – part of that distance will be in a
congested loading area
• I will probably want a speed limit on that area
different than for the bench as a whole
My First 150 feet in a Congested
Loading Area
Another line appeared for more of the route. I entered 0% grade
Because the bench itself is level.
Now I need a speed limit
Congested Area Guidelines
(From Surface Mining - First Edition)
I’m going to consider my conditions average.
Enter the Data and a Description
Now I need to deal with grade and rolling resistance
Roads Produce Forces that Influence
Vehicle Movement
• Roads slope up hill and down
• This will cause gravity to work for or against the
forward movement of the truck
• It is called grade resistance
• The common unit of Grade Resistance is %
• Example – if a road goes up 1 foot for every 10 feet of
distance it is called 10% grade (note that 1 is 10% of
10)
• Note that we are not using slope angles
Other Forces
• Trucks are subject to wind or air resistance
• Air resistance increases dramatically with speed
• For a car going 70 mph wind resistance is one of the largest
opposing forces
• Haul trucks lumber along at slow paces and wind
resistance is usually considered 0 for an engineering
approximation.
Rolling Resistance
• Tires Sink into Ground - softer ground sink
more
• Tires Flatten
• Driving uphill out of a rut on a flat tire spot
• Need to Know Underfoot conditions and
Type of Tire (Radial or Bias Ply)
Grade Resistance in %
• Number of feet up (or down) for every so
many feet forward (or backward).
• I’m on a level bench so I go up 0 feet for
every 100 feet – thus my grade resistance is
0%
• Rolling Resistance will depend on the road
and the tires.
Hard Smooth Stabilized Surface
I like 1.7 for our established haul road with
Radial tires
Enter the Information
Next 400 more feet across the bench.
Enter the Data
Now what about the grade resistance – what is positive and what is
Negative?
Sign Conventions and Resistance
• Standard Convention
• A positive resistance resists motion
• A negative resistance favors motion
• Note that rolling resistance will always be positive
because it always resists motion no matter what
the direction
• That 10% grade out of the pit is +10
• That 5% grade down the canyon is -5
Now We Need to Do the Return
Route
I will click on
The return
Radio button
If the haul road
Back is unique
I enter as before
If I just reverse
Directions I can
Click Mirror
Haul Road (and
It reverses route)
The Forth Tab Lets you Match a
Truck Fleet and Route for Study
Since we have only entered one of each this is not to big a choice. If you’ve entered more
Than one route or truck fleet you could have quite a few choices.
Tab 5 – Production and Costs has
Large Number of Subtabs
As before you generally work the subtabs left to right.
Oddity #1 – Double Select Buttons
The select process is really two tear. The select tab lets you create a subset of cases to work
With. Ultimately FPC can only do one case at a time – the second select picks one from the
Sublist we created. (Again my one truck one road combo is boring).
One of the Most Critical Tabs
The Cycle Time Tab is Where
We Deal with Load Time,
Dump Time, and any fixed
Delay times on the route.
Before We Will Be Allowed to Do Anything
We Must Disclose Our Unload Time
FPC will start blocking your
Other inputs on the page
Until you cooperate.
Typical Unloading Arrangements
• Back the truck up – line it up with a dump point and dump
into the point
• Such as back-up to a gyratory crusher and dump into it.
• Requires precise placement
• Depending on number of open gyratory dump points trucks may
have to wait for a previous truck to get clear.
• Back up to a general point and dump
• Such as backing up to the edge of a leaching pile and then
dumping material over the side
• Requires less – line up
• Usually more open space and not forced to wait for a truck in front
of them
Unloading
• Tailgate
• The truck dumps pulling forward and spreading load
behind it.
• May or may not require a total stop of the truck
• Truck is moving forward and avoids backing manuver
• Truck ends its unload cycle already in motion
• Pull forward to dump point
• Pull over a dump point and unload
• Usually done with bottom dump trucks
Size of Truck and Difficulty of
Maneuver Control Time
• Typical Mining Truck can dump the bed in about
30 seconds
• Big lumbering one might be closer to 40.
• A general backing maneuver takes about 30
seconds
• Make it more like 45 seconds if the dump target is
small or the truck real big
• Make it about 1 minute if I have to wait for another
truck to clear out first
• If you can just pull forward and stop on a point it
can probably beat 10 seconds
My Case
• I’ll assume I back up to one of two gyratory
crushers and dump into the crusher
• I have 2 gyratories so I won’t have a wait time.
• I do have a big truck backing up to a small
specific target
• 45 seconds
• I have a big truck bed so I’m about 40 seconds to
dump
• Total – about 1.5 minutes
Input and Enter and I Get My First
Truck Cycle Estimate
Note that my dump strategy means
I will make a full stop at the end
Of my haul and will be starting my
Return trip from a full stop
Position
(This would not be true of all
Unloading arangements)
Now We Reconcile Loader Passes,
Fill Factors and Truck Volumes
We have discussed the
Principles before but now
We have to get it right.
I Remember I Needed 4 Passes at
80% Fill
Note – this is a great place to
Find or commit a screw-up.
If my loader was a lousy
Match for my truck I’m going
To get a bad number of
Passes.
The program does not check
To see if your fill factor is
Realistic for your material.
You can input garbage – but
Guess what you’ll get!
You must work this till you get an integer number of passes.
The program will not check you.
Now I Need to Deal with My Load
Time
The times that come up on the list are for smaller loaders doing single truck
Loading under ideal conditions.
The Loader Cycle Time
• How Long Does it Take a Loader to take a scoop –
turn – dump it in a truck and return to a ready
position for the next scoop.
• Hydraulic Shovels have fastest movement
• About 20 seconds for a little one with an easy dig
• About 35 for a big one
• Front End Loaders are worst – they have to back,
maneuver and scoop.
• About 40 seconds for a small one
• About 50 seconds for a big one
For A Cable Shovel
Graph of Dipper
Size and Digging
Conditions for
Impact on one
Loader Cycle.
But Wait – There is More
• Most manufactures cheat on published data
• (This does not impact front end loaders)
• They assume the angle between the digging
face and dump point is 90°
• For the most common configurations the angle is
120° so the swing time is longer
• To adjust for 120° swing the published cycle needs
to be multiplied by 1.1 to 1.2
Getting My Number
• I Have a Cable Shovel with a 56 yard dipper
• I’m assuming an average blasted face which
is “Hard Digging” for a Cable Shovel
I’ll be about 32 seconds * 1.15
About 37 seconds
Now Lets Consider the Hauler
Exchange
This is the time it takes one truck to pull away and then another to move in and
Spot and be ready to load. For larger trucks this is more like 1 minute rather than
0.7
This leads to what is the First Bucket Dump?
First Bucket Dump
It is assumed that during the lag time when one truck is pulling out and another
Pulling in that the loader is getting a scoop of material ready. When the truck is
Positioned only the short time to dump the dipper is involved.
Actual Times Depend on Field
Loading Configurations
• Depends on the type of equipment used
• On the space available
• Shovels and Hydraulic Excavators tend to
load in one set of ways
• Backhoes have some variations
• FEL have some unique ones
Single Truck Loading
Loader near the face
Truck backs up next to the
loader on the drivers side
(Gives the loader operator a
better view
Loader working into cut in the
face
Loader swings about 120
degrees to dump
Advantages of Single Truck
Loading
• Simple
• Truck doesn’t have to back tires into the
rockiest areas
• The shovel faces armor of the tracks into
the dig face
• Shovel operator has optimized view of truck
bed target
Disadvantages of Single Truck
Loading
• Backing into place can take around 1
minute and may require a spotter
• Loaders expensive and idle
• Back time is an unproductive bottleneck
• Can form large ques because trucks tend to bunch
• 120 degree swing angle can be slow
• Manufactures often rate on 90 degree
More Disadvantages
• Limited Space Available for Oversize
Material
• Can set to side
• Do a bowling ball drop into truck
• Hydraulic shovels can set - but cable shovels drop
bucket bottom open
• Extension cord problems with electric
equipment
• Cord has to cut across truck path
• Putting on poles can cost time
Using Single Truck Loading in FPC
• It’s easy – the screen layout assumes single
truck loading
• Do it just like we just finished doing.
Double Truck Loading
Same Arrangement as
single truck loading only
the trucks pull up on both
sides
Advantages of Double Truck
Loading
• Second Loading Spot Allows a second truck
to spot during loading operations
• Avoids dead time on the loader
• Doesn’t help the truck cycle time other than
eliminating some queing
Disadvantages of Double Truck
Loading
• Still have extension cord problems on
electric units
• Oversize boulder problem is now even more
severe
• Forces Loader operator to load on the blind
side (most big loaders put the cab to one
side of equipment)
Doing Double Truck Loading in
FPC
• Loader cycle time
• On one side of the truck the loader operator will
not actually be able to see the truck bed till
he/she is on top of it
Cab
Shovel
Note how late the operator will
Be in actually seeing his dump
Target.
You’ll need to slow the cycle down
About 5 to 10%
Double Truck Loading in FPC
• Hauler Exchange time
• By having a second load point the loaders wait
for another truck drops to 0
• Hauler Exchange time goes to 0
• Side Effect
• First Bucket Dump now takes the full cycle
time since the loader did not have a time break
while trucks backed in.
Another Impact
• The Loader has no truck wait time
• The truck may not wait for another truck to
pull out but backing into place still puts
about 30 to 45 seconds onto a truck cycle
• For single truck loading FPC automatically
adds the loader exchange time to both the truck
and the loader.
• By zeroing that time for the loader – I have lost
the back time for the truck
I Need to Add This Time Back for
My Truck
I would add about 0.75 minutes
Into my dump and maneuver time
(even though the extra
Maneuver is actually at the load
Point).
If You Get The Feeling I’m Forcing FPC to do
Something it was not Designed For
• Your Right
• FPC was designed assuming all trucks use
single truck loading
• They left a loop-hole large enough to allow it to
do something else.
Drive By Truck Loading
Shovel Lines up Along
the face
Trucks pull forward and
stop beside the loader
Shovel Swings 90 to 180
degrees to dump
Advantages to Truck Drive-By
• Greatly Reduced Spotting Time - no
backing cycle
• Cable doesn’t cross the Trucks Path
• Can Set Oversize Beside and out of the way
• Machine marches on a steady forward
advance
• Can do in a narrower space – your working
benches don’t have to be as wide.
Disadvantages of Drive -By
• Often have problems with dipper swinging
over the top of the drivers cab
• Loader gets revenge for the truck running over
its extension cord
• If the dipper comes open your truck driver can
get dead
• Trucks get to drive those expensive tires
through spills
More Disadvantages
• Lack of spotting makes it a one shot that
can lead to long swings
• Tracks are broadside to long face area
Doing Drive-By in FPC
• If the truck drivers stop well this will get a 90°
swing – will speed up the loader cycle
• Lower your loader cycle time about 10%
• One truck still has to pull forward and another
follow in
• This is about a 10 to 15 second ordeal instead of a 45
second to 1 minute ordeal
• Put in a smaller time
• Since this affects truck and loader alike there is no need
to add extra time to the truck dump and manuever
FPC and Drive-By
• The Truck change-out time does indeed
reduce the first pass time for the loader
• First Bucket Dump = Loader Cycle – Exchange
Time
• Since Drive-By is often used in strip pits,
Cat’s FPC accommodates it without really
forcing things.
Modified Drive-By (Or Getting
Fancy)
• Shovel in Drive-By Position
• Truck Drives up to Shovel as if it was a
drive-by
• Loading drops onto a moving target
• While the Loading goes for the next bite the
truck backs into a single load like position
• Shortens swing distance
Advantages
• Get most of the positioning advantages of
single truck load without the idle spot time
Disadvantages
• Dump onto a Moving Target
• With swinging over cab can be a real
adventurous feeling for driver
• Gets the tires into some real rocky
conditions
Modified Drive-By in FPC
• Loader cycle time – usually no change
• Loader exchange time – drop to 0
• No need to add time to truck dump cycle –
he spots while the loader scoops
• Loader First Bucket Time Increases
• The loader is trying to dump onto a moving
truck
Backhoe Loading Methods
• Backhoe works below grade
• Can allow work to be kept off wet pit floor
• can also provide multi-level loading
• Backhoes generally need good size machine
relative to bucket. Doesn’t wear as well generally used for special conditions
Can Work Double and Single
Truck Loads
Can also Load on Multiple
Levels
Multilevel Loading
• Double Loading configuration
• has extra room for oversize and still two trucks
• Because truck has to come in on right level
does require some additional advance data to
send truck to right spot
• Can also get 3 position loading
• often a bit of overkill
FPC Handling
• Like Single or Double Truck Loading
• Remember to use loader cycle time suitable
for backhoe
• Since backhoe buckets tend to be small you
are more likely to have 5 to 7 passes to load.
Front End Loader Configurations
• FELs are less expensive than the trucks and
are mobile
• Makes practical to consider more than one
loader providing loading service
• Limited lift heights make truck match more
critical
• Tires can tear up bad underfoot
Single Truck Loading
Common Loading Arrangements
• Drive By Loading
Arrangements Putting More Than
One Loader at a Loading Point
How to Chain Load in FPC
• FPC assumes the number of loaders is equal to the
number of load points
• If I need 5 loaders to Chain Load a Truck
• Lie – tell FPC you have a loader with a load cycle time of 0.05
minutes
• Tell it your loaders first bucket is also 0.05
• (When you do enter cost tell FPC your one loader that
is as fast as 5 loaders also costs as much as 5 loaders)
• When you count your loaders at the end of the computer run
multiply the number of loaders by 5
• This gets the truck loaded in the right time
• The problem is if the program sends another truck to be loaded
0.25 minutes later the loaders will not be ready to chain load (it
takes each loader about 0.75 minutes to really scoop material
and load it).
Building in loader lag time
• Of the 0.75 minutes a real cycle takes about 0.05
is the dump
• This I did account for so I have 0.7 minutes left out
• While other loaders are loading the first has time
to start its cycle
• In this example I used 5 loaders to chain load
• There was 4*0.05 minutes while other loaders worked
• Now my unaccounted time is 0.5 minute
Entering the Loader Lag Time
• Look at the Hauler exchange time
• What really happens is the truck just pulls
through the chain and is loaded on the fly
• Thus there is no real hauler exchange time
• To Cope with Loader Lag Time
• Lie – in this case say there is a hauler spot time
of 0.5 minutes
• This will keep FPC from sending the load point
more trucks than it can really handle.
Now We Have Problems With Truck
Cycle Time
• The truck now has 0.5 minutes added to it’s cycle
that does not exist
• Lie – cut the dump time by 0.5 minutes
• Now the truck cycle time is right
• One more truck adjustment
The haul end speed is about 3 to 5
Mph – not 0. The same is true of
The start speed.
Tandom Loading
• This time I put two loaders on one truck
• The truck backs between two loaders that
then load it from both sides
Using Tandom Loading in FPC
• Tell FPC you have one loader
• But this loaders’ cycle time is twice as fast as a
normal loader
• Its cost is also twice as much as a single loader
• When you count up the number of Loaders at
the end of the run – remember to double the
number of loaders you buy
• The money for this was already handled when you
created “one” loader that cost as much to buy and
operate as 2
The First Bucket Load Time
Problem
• While the truck spotted the loaders got ready to
dump – thus they only need 0.05 minutes for the
first bucket.
• The FPC problem – it allows one bucket to take only
0.05 minute – in reality two buckets go in at the same
time
• Solution – Lie
• It takes about 0.7 to 1 minute to spot the truck
• Cut the time savings from the zero time second bucket
off of the spotting time.
Staggered Tandom Loading
As the truck comes in the first
Loader hits it on the fly like it
Was chain loading.
The truck then spots
During that time the two loaders
Were filling their buckets and
Are ready to go in dump time
Only.
Illustrative Case
• Suppose the truck will take 4 passes to load
• It will take the truck about 1 minute to spot
• During that 1 minute loader #1 has dumped the
first bucket in
• Loaders #1 and #2 have loaded buckets and are
ready to dump in 0.05 minutes
• At the end of 1.05 minutes the truck has 3
buckets in place
My Motion Timing Continued
• Now Loaders #1 and #2 go for another
bucket
• Loader #1 takes its bucket and positions for the
next truck
• Loader #2 dumps its bucket into the truck
• This takes 0.75 minutes
• 1.8 minutes after the truck comes in to fill –
it is out the door and loader fleet is ready
for the next truck
Now Lets Try to Get That One into
FPC
• We report the truck exchange time as 1
minute
• We now have 0.8 minutes to put in 4
buckets of material
• Tell FPC the loader cycle time is 0.2 minutes
• Tell FPC the first bucket time is 0.2 minutes
• Done.
Front End Loaders
• We are not using Front End Loaders in this
example – but front end loaders are a
trickier match to trucks
• You need to check loading height
• How high must the loader lift the material to
get it over the side of the truck and then nicely
centered in the truck bed.
Loading Height
21’ 5” to get over the side of a Cat
793
Check Out a 980
A 980 can only get up to about 11 feet – no go on 21.
In Fact a 994 (The Big One) Cannot
Dump Above the Edge of a 793 Truck
Be Careful of loading height limits for Front End Loaders
Commentary on Loading
• We have spent tremendous amounts of time
analyzing miniscule details of such things
as how a truck loads or dumps – Why
• Suppose we lower the cost per ton for loading
and hauling ore by 1c
• 9 million tons is $90,000 – your salary for the whole
year
• Little parts of a cycle done millions of time
each year become big differences
Penny Pinching In Perspective
• If a mine comes out non-economic the first
impulse is to begin nit-picking every dime
• The decisions that shift NPVs by hundreds of millions
of dollars deal with mine size, mine method, cut-off
grade, and financial structure
• If the “Air-Craft Carrier” sized decisions have been
made wrong – penny pinching will usually not save the
day.
• Don’t rely on Penny Pinching to decide whether you
get to “play the game”
• Penny Pinching deals with how you play the game –
after you get into the game.
Understanding How Loading Relates
to Other Mine Plan Issues
• Loading Configurations change the width of the space
needed for loading
• Drive-by is usually chosen because it works in narrower spaces
• Your working bench width influences your working slope
which greatly alters your stripping ratio – a major effect on
economics.
• Your working bench width also controls the size of a
practical mining “push-back” in an open pit mine
• Sketch out your loading plan considering vehicle sizes –
berm widths, prudent clearances and turning radiuses
• Then pick your loading configuration.
Loading Configuration and Mill
Operation
• Some of the Loading configurations discussed can
greatly alter the truck loading time.
• For an open pit where 30 minutes is a common truck
cycle, saving 1 minute off of loading time will probably
not revolutionize cost
• It can greatly alter the number of trucks that one
loading point can handle
• This in turn can change the number of loading points
• Smaller numbers of loading points or loading
points close together usually cause feed quality to
the mill to swing more wildly.
• Mills hate unstable ore conditions and usually protest
by sending recoveries to – well you know where.
Point
• Understand that just a few numbers going
into FPC represent major decisions in how
you will run the mine
• Make wise decisions about how to run the
mine and then make your FPC entries match
those decisions.
• Don’t just blow numbers into FPC and expect
good results.
Now I Will Close In On That Rough
Design I Talked About
I’ll use the Fleet Size
Sub-Tab what it does is
Show me what I can do
With a variable number
Of trucks and 1 loader
(Remember I wanted to
Avoid committing to
A number of trucks or
Loaders until I had an
Idea of cycle time)
Tip on a Frustration
The default number
Of trucks FPC tries
Is 1 to 4.
I wanted 1 to 10.
I typed in the 10
And nothing
Happened.
I had to click in
Another field to make
The change take.
Look at Results
Things I see #1 – I can reach 9 million tpy with just one loader
#2 – I need 4 of 5 trucks
#3 – My production per truck keeps going up fairly linearly – suggests that I
am not really “over-trucking my loader”
Jump Back to My Cycle Times Tab
It takes about 38 minutes for a truck
To make a trip but only 3 minutes
To load
38/3 = 12.67
I would need 13 trucks to over-truck
My loader.
(Over-truck means I have so many
Trucks that the loader is the
Production limit).
This is under-trucked – availability of
Trucks controls production.
What Did I Do?
• I just got the program to help me ratio my trucks
and loaders without me doing any guessing or hand
calculation.
• Now I’ll go back and change # of trucks to 5.
Check My Fleet Production
Yup – I need 87% of my scheduled
Time to do 9,000,000 tons of ore
With 5 trucks and one cable shovel.
Issues that Remain
• I need to check my Ton-Mile-Per-Hour
Ratings
• (make sure I’m not running my trucks around
so fast that I overheat and blow-out the tires)
• I need to enter my cost data and see the cost
• I need to consult with my mill and ore
reserve modeling people.
Why the Consult
• I am feeding the mill from one load point only
• My ore reserve people can estimate the typical changes
in ore grade going to the mill
• My mill people can tell me whether this will upset my
recovery rates at the mill (financially upsetting the mill
will cost more at most metal mines than optimizing my
truck and loader fleet can save)
• It is very possible we will be told that our trucks
and loaders are too darn big for practical grade
control at a mine this size.
Lets Put the Tire Heating Issue to
Rest
A Cat 793 needs 46/90R57 Tires
The tire is rated at 630 ton miles per hour
(ie a load of 1 ton on 1 tire traveling at 1
Mile per hour is 1 ton mile per hour)
(The tables are from the Cat Handbook)
Enter This Into FPC
I am going to the fleet input tab and using the Tmph Limit field.
Now For Results
Go for the Production and
Cost Tab and the
Tire Temp Subtab.
We See the Average Number of Tons
Load on Each Tire
Interesting to note that it’s the front tires that take the worst load (these tires are
Not double like those in back)
We Check Tire Heating at the Technical
Maximum Speeds for the Truck
As we can see we are just barely over-rating on the front tires.
Then We Adjust
A real operator never operates the truck and mechanical theoretical maximum and
A real operator does not work an 8 hour shift with no breaks (remember the 84%
Shift efficiency). Assume this allows some tire cooling and we are at 82% of
Tire capacity. We won’t blow out the tires.
(if the temperature is 120 or 140 for long periods of time we would have to reduce
The tire rating. If we ran a driverless truck we might also have an issue).
Time for the Cost Issue
• For this I will simply illustrate putting in
information for another truck. (not our 793)
but it gets the point across.
Truck Production Costs
• Divided into Ownership and Operating
Costs
• Ownership includes
• Annualized Investment Costs
• Taxes and Insurance
• Tax advantages
• Operating Costs are Incurred as Vehicle
performs service
Operating Costs
•
•
•
•
•
Fuel
Tires
Lubricants
Repair
Operators
Setting Costs In FPC
On Fleet Input Tab
Use the Hourly
Cost Button
Sub Menu Divides Owning and
Operating Cost
Using Menu Requires a lot of side
calculations
Latest Editions of Cat Handbook
Has removed cost estimating
Sections. Have to revert to
Earlier issues (which we have
Online)
Lets Go for Fuel First
Getting Fuel Consumption Rates
We get
About
17 gallons/hr
Our truck is
A 777
We assumed
$2.0/gal.
17*$2=
$34/hr
Our Conditions are Medium
Info from 29th Ed Cat Handbook
Input Our Fuel Cost
(Ok – you would not buy $1/gallon really)
Lets go for the Lube
Filter, Oil and Grease
Enter the Lube/Filter/Grease
Terex rule of thumb was
High and 10% of fuel
Undercarriage is a dozer
Or tracked machine
Thing – 0 here
Repair Reserve Next
Vehicle Life Impacts Repair Costs
Table from Cat Handbook
29th Edition (online)
Cat 777 will last 40,000 to
60,000 hours
Under Average Conditions
About 50,000
Repair Reserve Tables
Cat 777 has a base
Repair reserve cost
Of $10/hour
Actual cost Varies with Life of
Machine
If we go for
A 50,000 hour
Life we will
Pay about
1.5 times what
Is in the table
Or $15/hour
Enter Our Data
Lets do Tires
Next
Need to Get Tire Life
Where most tires wear out
But some cut is zone B
An average is 3,000 hours
If retread cost is about 1.5
Times normal tire and
Life is about 1.75
Cat Handbook does not
Give a cost.
Western Mine Cost Service Has
Books of Costs
Including Tires in the
Supply section
This resource is
Available online for
Students or by
Subscription fee for
Commercial users.
Find Our 100 Ton Cat 777
Lists about $8,881
A Calculation of Tire Cost
• 6 tires * $8,900 each is $53,400
• Because of heating considerations I’m not
retreading
• $53,400 / 3,000 hours = 17.8/hour
Adding into FPC
Now Lets Go for
Operator
Western Mine Cost Service Has
Labor Surveys
Production Truck
Drivers getting
About $15.6
Another Source Is the US Bureau of
Labor Statistics
Note that I can pull
Pay and Benefit by
Area and Occupation
Industries Are Listed By NAICS
Code Numbers
Find the Best Match
Looks like mine
Machine operators
In quarries average
$15.9 /hr
Comment on Estimating
•
•
•
•
•
•
In addition to books, manuals and internet sources
Remember the Buddy Network
Excerpts from Trade Journals
Your Companies Own Historical Cost Records
Local Union Contracts or State Wage Scales
Vendor Quotes
Cooking Our Estimate
• Normally there are other costs
• Unemployment, workers comp, social security,
vacation, health etc.
• You can calculate specifically or use rule of
thumb estimating
• 40-60% burden
• I’ll go at low end for quarry
• 1.4 * $15.75 = $22.05
Input and Switch to Ownership
Hmm – Looks like
It costs about
$70.2/hr to run.
One of My First Issues in How Long
it Will Last
Input My Knowns
I already scheduled
2772 hrs per year
With 80% availability
In my example
I also know the truck should last about 50,000 hours
At 2,218 hours per year that about 22.5 years
Getting My Truck Cost
Using Western
Mine Cost
Service
Looks like I’ll be
About $1,062,000
For my Cat 777
Price and Tires
Truck weighs 161,000 lbs or
1,610 units of 100 lbs – use $4/100
Weight rule to estimate freight about
$7,000 double for assembly
Most Prices are Quoted at the
Factory – Your have freight
And assembly (I added a little
Extra as you saw)
Tires are a wear item so often
They are deducted from the price
To avoid double counting
The Issue of Taxes and Insurance
Rule of thumb is that Tax and Insurance
Are about 5% (2.5% each) of
Average Annual Investment
(I wish they would call it average annual value)
As vehicles values go down so does tax on insurance
Average value of calculation is
(N+1)/2N * Cost where N is life
Substitute and crank
33/64*$1,600,000 = $825,000 * 0.025 = $20,625
Griping About FPC
• FPC does not handle time value of money
• Taxes and Insurance are high in the early
years and low in the late years
• A mathematical average does not show what
this can do when investors are looking for a
return on money
The Interest Problem
• If money is borrowed most of the interest
comes early
• I’ll show a method for getting time value of
money into it even if FPC tries to ignore it.
From Engineering Economics Get the Interest
Rate Comparison Spreadsheet
Standard Fixed Period Compound Interest Loan
9
1
0.09
1
0.09
10
1600000
0
0
0
0
0
Interest Rate
Number of Compounding Periods/Year
Period interest rate (as a decimal)
Number of Payments/Year
Payment Interest Rate (as a decimal)
Years for Loan Payoff
Loan Amount
Down Payment Required
Set Up Fees
Set Up Fees Rolled into Loan
Points Up Front
Points Rolled into Loan
249312.1 Initial Guess for Payment
249312.1
249312.8
893121.7
0
Payment Amount
Final Payment Amount
Interest Paid
Fees Paid
Put in that I borrow
Money at 9% over
10 years to pay for
The Truck
0 Points Cost
0 Points Cost
The Spreadsheet Gives a Yearly
History of Interest Payments
Period
1
2
3
4
5
6
7
8
9
10
11
12
Debt
1600000
1494688
1379898
1254776
1118394
969737.6
807701.8
631082.9
438568.3
228727.3
0
0
Interest
144000
134521.9
124190.8
112929.9
100655.5
87276.38
72693.17
56797.46
39471.14
20585.46
0
0
Payment
249312.1
249312.1
249312.1
249312.1
249312.1
249312.1
249312.1
249312.1
249312.1
249312.8
0
0
Principal
105312.1
114790.2
125121.3
136382.2
148656.6
162035.7
176618.9
192514.6
209841
228727.3
0
0
Use Excels Copy function
And copy the interest
Column and paste it into
Class Assistant
(Another Engineering
Economics Spreadsheet)
Paste My Interest Cash Flow Into the
Cash Flow Analyzer in Class Assistant
Get the Total Life Cycle Cost of the
Interest
A typical mine looks
For 15% rate of return
The truck goes into
Almost immediate
Service – time zero
Lasts for 32 years
An equivalent stream
Of interest over 32
Years is $79,378
Plug it Into FPC
I could have done
The total life
Cycle cost trick to
The Insurance
And Property Tax
Too
At this point I know it costs me
$107.85/hr to own the truck
When I Click Ok on the Subscreen I Know
Have Total Hourly Cost for My Truck
See! There it is!
This Still Needs to Be Done for My
Loader
• Much will be the same as we just did for our truck
• A Couple tid-bits for cable shovels
• The repair cost is a function of digging conditions and
tonnage moved
•
•
•
•
Very Hard 5 cents/ton
Hard 4 cents
Medium 3 cents
Easy 2 cents
• Cable Shovels use about 0.6 KWH of electricity
per cubic yard of loose rock moved.
FPC Strengths and Weaknesses
• It goes into truck and loader fleets in a very
complete way.
• Weakness – It calculates a specific load of material
over a specific road with a specific truck fleet
• May be more than one road to move the load to the
destination
• FPC has no selection capacity beyond what you select
• MineSight has a built in haulage routine
• If there is more than one route it just picks the shortest
• In practice roads may have different capacities and you
regulate traffic flow on the fly
• No standard package can optimize this
FPCs Catastrophic Weakness
• Probability of Available
• It treats the entire truck and loader fleet as one
entity each.
• Ie – if the trucks are 90% available then the entire
truck fleet is available 90% of the time and the
entire fleet is down 10% of the time.
• If loaders are 90% available then all loaders work
90% of the time and all loaders are down 10% of the
time
• Over-all production available 0.9*0.9 = 0.81
• 81% of the time
The Impact
• FPC is right if you have 1 truck and 1 loader
• Reality of 5 trucks is that
•
•
•
•
•
•
You can have 5 trucks running
4 trucks running
3 trucks running
2 trucks running
1 truck running
The whole darn fleet down
• No it does not all average out – you bunching and fleet
match very
• FPC under-predicts your fleet capacity
• (some suggested cycle times are optimistic so they get some
cancelation by luck – but for millions of dollars luck is rather
lame)