Injection Moulding Technology

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Injection Moulding Technology – IMT3
Welcomes you to
Injection Moulding Technology - Part 3
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Injection Moulding Technology – IMT3
Introduction
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Safety
Telephones
Registration
Practical sessions
Smoking
Workshop access
Refreshments
Personal issues
Messages
Your contribution
Injection Moulding Technology – IMT3
Aim of course
To provide delegates with an in-depth knowledge
of the injection moulding process, in order to
competently and safely set up a range of moulding
machines, to achieve product quality and output.
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Injection Moulding Technology – IMT3
Testing
Through out the course there will be;
Lesson Assessments
Class Exercises
Evening Assessments
In your manual section 1, PAGE 8
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Injection Moulding Technology – IMT3
Knowledge Assessment
Conducted at the end of the course, successful
completion of which:
Awards a P.T.I.C Level 3 Polymer
Processing Certificate.
Will assist personnel working towards the
achievement of an Injection Moulding Diploma
certificate.
Allows progression onto practical element within
Injection Moulding Technology - Part 3, resulting
in the full award of a P.T.I.C Approved Technician.
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Injection Moulding Technology – IMT3
Timetable
DAY 1
09:00
09:15
10:30
10:45
12:30
13:00
13:30
15:00
15:15
16:00
16:45
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ADMINISTRATION & INTRODUCTIONS
MACHINE CONSTRUCTION – CLAMP END
BREAK
MACHINE CONSTRUCTION - INJECTION END
LUNCH
SELF DEVELOPMENT (review morning session)
MACHINE CONTROL & INSTRUMENTATION
BREAK
MACHINE CONTROL & INSTRUMENTATION
HEALTH & SAFETY
FINISH (evening assessments and Quality)
Injection Moulding Technology – IMT3
Timetable
DAY 2
09:00
10:30
10:45
12:30
13:00
13:30
15:15
15:30
16:45
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QUALITY(review evening assessments)
BREAK
MACHINE PRACTICAL No 1
LUNCH
SELF DEVELOPMENT (review morning session)
MACHINE PRACTICAL No 1
BREAK
MACHINE PRACTICAL No 1
FINISH
Injection Moulding Technology – IMT3
Timetable
DAY 3
09:00
09:15
10:30
10:45
12:30
13:00
13:30
15:15
15:30
16:45
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REVIEW HOME WORK
MOULD TOOLS
BREAK
POLYMER MATERIALS
LUNCH
SELF DEVELOPMENT (review morning session)
PROCESS & TROUBLESHOOTING
BREAK
PROCESS & TROUBLESHOOTING
FINISH
Injection Moulding Technology – IMT3
Timetable
DAY 4
09:00
09:30
10:30
10:45
12:30
13:00
13:30
14:30
14:45
15:00
17:00
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HOME WORK REVIEW
MACHINE PRACTICAL No 2
BREAK
MACHINE PRACTICAL No 2
LUNCH
SELF DEVELOPMENT (revision of course)
MACHINE PRACTICAL No 2
BREAK
DELEGATE FEEDBACK
END OF COURSE ASSESSMENT
FINISH
Injection Moulding Technology – IMT3
Injection Moulding Technology
Part 3
Machine Construction
Clamping End
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Injection Moulding Technology – IMT3
Session aim
To provide an in-depth understanding of the clamp
unit construction, operation and setting, including
variations in terminology.
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Injection Moulding Technology – IMT3
Session objectives
By the end of the session you will be able to:
State the functions of the clamping unit.
Name design alternatives for the clamp unit.
Explain how to set and adjust the locking tonnage.
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Injection Moulding Technology – IMT3
Terminology
Whenever possible: Daylight = 2-3 x depth of moulding
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Injection Moulding Technology – IMT3
Terminology
Mould Height
Moving Half
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Fixed Half
Injection Moulding Technology – IMT3
Clamping end – Component Parts
Moving
Platen
Ejection
Fixed
Platen
Tie Bar
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Mould
Clamping
Cylinder
Injection Moulding Technology – IMT3
Direct hydraulic lock
Single Hydraulic
Cylinder
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Injection Moulding Technology – IMT3
Direct hydraulic lock
Advantages
1. Self lubricating
2. Low maintenance
3. Larger tonnages
4. Tonnage set more
accurately and
easier to adjust
Disadvantages
1. Slower movements
2. Larger pumps
3. Seals expensive
to replace
4. Increased power
requirements
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Injection Moulding Technology – IMT3
Setting the mould height
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Tailplate position adjusted
1.0mm
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High pressure applied
1.0mm
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Toggle locking mechanism
What if it doesn't reach ?
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Spacer
Injection Moulding Technology – IMT3
Hydraulic Driven Gear for Mould Height Adjustment Toggle Lock
Machine
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Double Toggle: Five point system
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Toggle mechanism
Advantages
1. Fast movements
2. Natural acceleration
and deceleration
3. No forces on the
clamping cylinder
when locked.
Disadvantages
1. High stress/strain
2. High maintenance
3. Links need lubrication
4. Usually smaller than
2200 Tonnes
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Injection Moulding Technology – IMT3
Ejection methods
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Clamp tonnage estimation
Calculate projected area: 4 x 3 = 12in2
Rule of thumb = 2 - 4 tonnes/in2
4”
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3”
Polycarbonate
12in2 x 4 = 48T
480 KN
Injection Moulding Technology – IMT3
Clamp tonnage estimation
Calculate projected area: 8cm x 7cm = 56cm2
Rule of thumb = 0.3 - 0.6 tonnes/cm2
POLYPROPYLENE
7cm
8cm
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56cm2 x 0.3 = 16.8T
168 KN
Injection Moulding Technology – IMT3
Clamp tonnage estimation
To be used as a guide line only!
CM = 0.3
INCHES = 2
PP
PE
PA
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0.4/0.5
3
ABS
PS
POM
0.6 Tonnes per Sq CM
4 Tons per Sq Inch
PVC
PC
PMMA
Injection Moulding Technology – IMT3
Clamp end - 7 point plan
• Zero parameters
• Obtain movement
• Set positions
• Set speeds
• Set ejectors
• Set tonnage
• Check mould safety
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Injection Moulding Technology – IMT3
Injection Moulding Technology
Part 3
Machine Construction
Injection End
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Injection Moulding Technology – IMT3
Session aim
To provide an understanding of the construction,
operation, setting up and terminology, relevant to
the injection unit of the moulding machine.
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Injection Moulding Technology – IMT3
Session objectives
At the end of this session you will be able to:
Describe the basic construction of the injection unit.
Name three zones of a general purpose screw.
Describe the design of PVC and Nylon screws.
Identify the function of injection unit process
parameters.
List commonly used nozzle designs and describe
their application.
Explain the term “specific injection” pressure.
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Injection Moulding Technology – IMT3
Reciprocating screw injection unit
Fixed
Platen
Reciprocating
Screw
Feed
Hopper
Feed Throat
Nozzle
Barrel
Check
Valve
Injection
Cylinder
Drive Unit
Barrel
Heaters
Carriage
Cylinder
Carriage
Complete the exercise in your course manual, Injection Unit Components.
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Injection Moulding Technology – IMT3
Screw rotation
What is back pressure?
What is decompression?
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Injection Moulding Technology – IMT3
General purpose screw
Metering
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Compression
Feed
Injection Moulding Technology – IMT3
Length to diameter ratio (LD ratio)
Hopper
Barrel
Diameter
60mm
Length 1200mm
Length = 1200mm
Diameter = 60mm
L/D ratio = 1200/60 = 20:1
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Injection Moulding Technology – IMT3
Compression ratio
Volume in this flight = 1
Volume in this flight = 3
Compression ratio = 3:1
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Injection Moulding Technology – IMT3
The check ring
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Nozzle & screw removal
End Cap
Nozzle
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Heater Band
Injection Moulding Technology – IMT3
Nozzle types
Open
Shut-off
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Injection Moulding Technology – IMT3
Spring loaded shut-off nozzles
Shut-off
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Injection Moulding Technology – IMT3
Hydraulic shut-off nozzles
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Nozzle seating
Nozzle with too
large a hole
Nozzle with too
shallow a radius
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Correctly sized
nozzle
Nozzle with
too sharp a radius
Injection Moulding Technology – IMT3
Hydraulic pressures
Maximum
Pressure
Set Injection Pressure
Switchover Point
180 bar
What is specific
pressure?
90 bar
Peak Pressure
Actual
Pressure
Holding
Pressure
50%
Speed
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Injection Phase
Holding Phase
Injection Moulding Technology – IMT3
Negri Bossi 100T
Specific Injection Pressure
Screw
Diameter
45
35
Hydraulic Intensification
Pressure
Factor
140
9.7
=
X
140
16
Screw Diameter
= 45 mm (4.5 cm)
Specific
Inj.Pressure
1358
2240
58
Piston Diameter
= 140 mm (14 cm)
Specific
Pressure
1358 Bar
Screw area = 15.9 sq. cm
Hydraulic
Pressure
140 Bar
Piston area = 153.9 sq. cm
Intensification factor = Piston area = 153.9 sq. cm
= 9.7
Screw area = 15.9 sq. cm
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Shot
Capacity
72
Injection Moulding Technology – IMT3
Hydraulic pressure - Specific injection pressure
psi
Specific pressure
(in front off the
screw)
bar
Typical 360 ton
moulding machine
2100
2055
25000
1800
1510
1500
20000
1200
1155
15000
10000
600
5000
300
0
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30
60
90
120
Reading at pressure gauge
150 bar
Injection Moulding Technology – IMT3
Mould cavity specific pressure
Flow path length =
200 mm
Wall thickness =
1.5 mm
Material to be
used is PVC
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500 bar
Specific
pressure
Injection Moulding Technology – IMT3
Projected area VS. clamp force
Mould projected
area = 600 Sq.cm
Specific pressure
was = 500 bar
300 tonne
3000 KN
Use the charts
provided in your
course manual
to complete the
clamping force
requirements.
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Injection Moulding Technology – IMT3
Projected area
750 bar
Specific
pressure
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Injection Moulding Technology – IMT3
Mould area VS. clamp force
90 tonne
900KN
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Injection Moulding Technology – IMT3
Injection Moulding Technology
Part 3
Machine Construction
Injection End
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Injection Moulding Technology – IMT3
Injection Moulding Technology
Part 3
Machine Control
&
Instrumentation
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Injection Moulding Technology – IMT3
Session aim
To provide an understanding of process parameters
and machine control devices to enable effective
setting of the injection moulding machine.
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Injection Moulding Technology – IMT3
Session objectives
By the end of the session delegates will be able to:
State the 5 control parameters for injection moulding
Describe how basic flow and pressure valves operate
Identify 4 types of positional control devices
State 3 types of injection moulding machine timer
control devices.
Describe the relationship between pressure &
speed within a hydraulic system of an injection
moulding machine.
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Injection Moulding Technology – IMT3
Machine control parameters
Temperatures
Pressures
Speeds
Times
Positions
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 1
A temperature closed loop control system can be
divided into three areas. What are they?
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Barrel temperature control
Heater
Closed
Loop
Controller
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Thermocouple
Injection Moulding Technology – IMT3
Factors affecting melt temperature
Shear
Back pressure
Screw rotation speed
Screw design
Residence time
Injection speed
Ambient temperature
Feed throat temperature
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 2
Name three types of heater bands?
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Injection Moulding Technology – IMT3
Heater band types
Mica
Ceramic
Ceramic (Knuckle)
Aluminium
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 3
How can shear heat be generated within the
barrel?
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Injection Moulding Technology – IMT3
Shear heat
Frictional heat created by screw rotation
Excess back pressure
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 4
Name three designs of thermocouples?
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Injection Moulding Technology – IMT3
Thermocouples
Where a pocket cannot be created, a band type
thermocouple might be used, and where the
temperature of a fluid is to be measured, one might
resort to a leak proof compression fitting
thermocouple.
Bayonet
Fitting
Armoured compensated leads
Compression Type
Ring Type
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 5
What is the function of a thermocouple?
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Injection Moulding Technology – IMT3
Thermocouples
Thermocouples are used to
measure or sense temperature.
Heater
Controller
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T/C
Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 6
How does a thermocouple work?
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Thermocouples principle
Metal 1
Hot
Junction
Millivoltmeter
Calibrated in oc
Cold
Junction
Cold
junction
Metal 2
The potential difference
(volts) can be related to the
temperature difference.
Fe wire
Hot
junction
Kon wire
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Thermocouple output
TYPE J - IRON/CONSTANTEN
TEMP DEG C
MILLIVOLTAGE
200
220
240
260
10.777
11.877
12.998
14.108
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TYPE K - NICR /NIAL
TEMP Deg C MILLIVOLTAGE
200
220
240
260
8.137
8.938
9.754
10.560
Injection Moulding Technology – IMT3
Thermocouples
International colour codes for thermocouple identification
T
Y
P
E
K
NICKEL CHROME/NICKEL ALUMINIUM NiR/NiAL
T
Y
P
E
J
IRON CONSTANTEN I/C Fe/con Fe/CuNi
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 7
Compare and contrast an ON/OFF temperature
controller to a PID controller. Which one offers
optimum control?
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Injection Moulding Technology – IMT3
ON/OFF controller
Potentiometric
200oC
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Injection Moulding Technology – IMT3
Temperature controllers
“PID control is very accurate at recording temperature”
P.I.D (Proportional Integral Derivative)
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Proportional
Droop error
200oC
10
30
50
70
90
100
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Injection Moulding Technology – IMT3
Proportional derivative
Droop error
200oC
10
40
70
90
100
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Slow approach
More power for longer
Injection Moulding Technology – IMT3
Proportional integral derivative
200oC
10
40
70
90
100
Slow approach
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Injection Moulding Technology – IMT3
Machine control & instrumentation
Question 8
Name three types of position controllers? In
addition, state which one of them is the most
accurate way at providing actual feedback.
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Injection Moulding Technology – IMT3
Positional control devices
Roller
Plunger
Limit switches
Limit switches are micro
switches, which
automatically start and stop
the movements of the
machine.
They may be of the plunger,
roller or roller lever type.
On/Off control
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Roller lever
Injection Moulding Technology – IMT3
Proximity switch
On/Off control
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Linear Variable Differential Transducer
LVDT
Variable control
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Rotary encoder
LVDT
Variable control
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Machine control & instrumentation
Question 9
List three functions of a timer and give examples.
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Injection Moulding Technology – IMT3
Categories of time
Categories
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Examples
Normal times
Holding time, cooling time,
open cycle time
Supervisory times
Mould safety time,
injection time, cycle time
Delay times
Delay screw back,
Delay injection
Injection Moulding Technology – IMT3
Fundamental principles of speed & pressure
Pressure is created by resistance to a flow of oil.
Pressure is controlled within the hydraulics
of an injection moulding machine by the use of
pressure relief valves.
The flow of oil is varied in the hydraulic circuit
by the use of speed or flow control valves.
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Pressure relief valve
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Injection Moulding Technology – IMT3
Flow / Speed control valve
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Proportional Speed Control Valve
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Proportional Pressure relief valve
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Injection Moulding Technology – IMT3
Moog valve
Microprocessor electronics which enables connection
to a PC, for remote or on-site diagnostic correction!
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Injection Moulding Technology – IMT3
Hydraulic injection pressure
Specific injection pressure
10 : 1 Ratio
180 Bar
1800 Bar
80 Bar
40 Bar
Peak injection pressure
50 Bar
If injection pressure is reduced what will happen?
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Essential principle
Remember!
Pressure affects flow (speed)
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Injection Moulding Technology – IMT3
The accumulator
Nitrogen
pressure
Nitrogen
Bag
Dampen pulsation's and
shocks within the system.
Allow immediate operation
of a service on demand.
Stores oil under pressure.
Provides high rate, hence
high actuator speed.
Pressure build up
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Oil flow
Injection Moulding Technology – IMT3
Mould fill and hold
(Example - 4 impression mould)
160 bar
Set values:
Injection pressure = 160 bar (max)
Injection speed = 50 %
Hold pressure = 40 bar
90 bar
Holding
Pressure
Injection
Pressure
40 bar
Cushion
0
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10mm
Hold position
(switchover).
Fill Time = 1.55 secs.
Injection stroke - mould 99% full
100mm
Injection Moulding Technology – IMT3
Injection end - 7 point plan
Set shot weight & hold pressure position
Set screw speed
Set injection speed
Set injection pressure
Set injection & hold times
Set cooling time
Set injection initiation
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Injection Moulding Technology – IMT3
Injection Moulding Technology
Part 3
Machine Control
&
Instrumentation
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Injection Moulding Technology – IMT3
Injection Moulding Technology
Part 3
Health & Safety
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Injection Moulding Technology – IMT3
Session aim
To provide an overview of the safety requirements,
relevant to the injection moulding industry.
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Injection Moulding Technology – IMT3
Session objectives
By the end of the session you will be able to:
Identify hazards associated with the injection
moulding process.
Name the safety systems required on a high
risk guard.
State a duty of the employee and employer
under HASAWA 1974.
List the necessary guard check requirements, as
stated within the BPF Code of Practice.
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Injection Moulding Technology – IMT3
Please Note!
The information presented during this training
programme is provided in good faith and for the
guidance of the delegates.
Polymer Training accept no responsibility for
alterations to legislation, which may have occurred
without prior knowledge of the Polymer Training
representative.
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A Rochdale plastics manufacturer has been fined £140,000 after
a Portuguese cleaner was crushed to death by a pallet of bags
weighing nearly one and a half tonnes.
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Injection Moulding Technology – IMT3
• Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995
•
•
•
•
•
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(RIDDOR) Change – 6 April 2012
From 6 April 2012, subject to Parliamentary approval, RIDDOR’s over three
day injury reporting requirement will change. From then the trigger point will
increase from ‘over three days’ to over seven days’ incapacitation (not
counting the day on which the accident happened).
Incapacitation means that the worker is absent or is unable to do work that
they would reasonably be expected to do as part of their normal work.
Employers and others with responsibilities under RIDDOR must still keep a
record of all over three day injuries – if the employer has to keep an accident
book, then this record will be enough.
The deadline by which the over seven day injury must be reported will
increase to 15 days from the day of the accident.
New guidance that explains the change will be available to download from the
HSE website on 16 January 2012.
Injection Moulding Technology – IMT3
Factories Act 1961 - Section 14
Machines made before 1993 governed by Factories Act
This Act was only applicable until 1997
After 1997 the Factories Act, Section 14 ceased to
be relevant to machine guarding
The Factories Act was superseded by EC
regulation ‘Work Equipment Regulations’ in 1993
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Health & Safety - UK Legislation
H.A.S.A.W.A. 1974
B.P.F. Code of Practice
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Machine guards
Normal
Fixed
High
Fixed
Fixed
Fixed
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Fixed
Injection Moulding Technology – IMT3
Other guards
Siemens Automotive
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Policing the law
The HSE have compiled their own guidance
sheets, that relate to various processes. These
can be obtained directly from the HSE and are
deemed to be the minimum requirements.
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Injection Moulding Technology – IMT3
Powers of the Inspector
They can enter at any time.
They can ask for an individual’s assistance.
They can issue an improvement notice.
They can issue a prohibition notice.
They can prosecute anyone who has
contravened a relevant statutory
provision.
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Corporate Social
Responsibility
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Injection Moulding Technology
Part 3
Health & Safety
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Injection Moulding Technology – IMT3
THE FACTORIES ACT 1961
SECTION 14
“Every dangerous part of any machine shall
be securely fenced or safe by virtue of its
position ”.
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HEALTH AND SAFETY AT WORK ACT - 1974
Duties of Employers - Section 2
To ensure the health and safety of all employees
by providing:
Safe plant and systems of work.
Safe handling, storage and transport.
Information, instruction, training and supervision.
Safe access and egress.
A maintained and healthy working environment.
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Injection Moulding Technology – IMT3
HEALTH & SAFETY AT WORK ACT - 1974
Duties of Employees - Section 7
To co-operate with the employer in matters
of health and safety.
Not to endanger him-/herself or others by
his/hers acts or omissions.
Not to misuse anything provided in the interest
of health and safety.
To report any unsafe situation.
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Injection Moulding Technology – IMT3
B.P.F CODE OF PRACTICE
The B.P.F. Code of Practice is NOT a statutory
requirement, but it may be used in criminal
proceedings as evidence, together with other
regulations, stating that statutory guarding
requirements have been contravened.
This code may be used by H.M. Safety
Inspectorate as a basis for it’s
enforcement procedures.
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