Machining
A systems approach
Manufacturing System
Ref: Chen, Joseph (2001). Educational Factory - From Design to Manufacturing Overview. Iowa State University
Manufacturing Cost
DFM
A basic understanding of Design for
Manufacturability, DFM, makes you a more
effective manager (ITEC) and/or teacher
(TechEd) by understanding the interaction
of [a] machining operation(s) within the
context of material processing with respect
to COST, QUALITY, and PRODUCTIVITY!
3 mechanisms toward DFM
1. Design-manufacturing Teams
2. Common CAD systems for design &
tooling
3. Understanding the value concepts
Training Needs
Comparison of Industry and Academic Perspectives on the Training Needs of the
U.S. Manufacturing Workforce (Prziembel, 1995).
Value Engineering
THE VALUE OF A PRODUCT IS THE
RATIO OF ITS PERFORMANCE TO ITS
COST
Obtaining the maximum performance per
unit cost is the basic objective of value
engineering (Gage, 1967; Mudge, 1971)
Economic Perspective
The “Economic” Perspective on Value Creation
For any product, a “value equation” can be defined...
Profit per unit - $$
Direct material cost
Direct labor costs
PRICE or
VALUE
Indirect labor costs
Determined by Customer
Non-reoccurring Cost allocation
Value Analysis
• Value analysis (VA) programs, as
generally conducted today (Bradyhouse,
1984), first challenge the design of the
product - searching for simpler designs that
will reduce cost while maintaining function.
A simple example
2 parts
Screw – $ 0.02
Washer - $ 0.01
1 part
Material
Cost
Screw – $ 0.02
Material
Cost
100 units = $ .03 * 100 = $ 3.00
100 units = $ .02 * 100 = $ 2.00
5 seconds/screw = 5 * 100 = 500
seconds (8.33 min)
5 seconds/screw = 5 * 100 = 500
seconds (8.33 min)
2 seconds/washer = 2 * 100 = 200
seconds (3.33 min)
(8.33 + 3.33)*($0.25) = $ 2.92
Labor
Cost
(8.33)*($0.25)= $ 2.08
($ 3.00) + ($ 2.92) = $ 5.92
($ 2.00) + ($ 2.08) = $ 4.08
Material + Labor = Cost
Material + Labor = Cost
Labor
Cost
Cost Comparison
NEW
1 part Design
$4.08 .69 ~ 30% cost
=
$5.92 reduction with new design
OLD
2 part Design
The other side
• Manufacturing Engineering
– Concerned with assuring that parts can be
manufactured and assemblies made and
tested to meet specifications with available or
potentially available techniques, tooling, and
test equipment at cost compatible with the
product’s selling price (Howell, 1982).
– The emphasis in manufacturing engineering is
to protect the interests of the manufacturing
function
VA/Mfg. Engr.
Relationship - Before
Product DevelopmentReview
Traditional: Sequential Product Development
Aka: “Throw it over the wall”
MARKETING
RESEARCH &
DEVELOPMENT
Voice of the Customer/
Market Opportunity
ENGINEERING
MANUFACTURING
Satisfaction of
Customer’s Needs
Concurrent Product
Design
Satisfaction of
Customer’s Needs
Design for Manufacturing (DFM)
Needed
• Concept decisions, product design, and
testing are performed prior to:
– Manufacturing system design
– Process planning and production
• TEAM approach is the KEY for success
2 Main streams of DFM
• Design for Machining (DFM) is
designing products with machining in
mind.
• Design for Assembly (DFA) is
designing products with minimum
assembly cost in mind
Design For Machining
Goals of Design For Machining
1. Reduce machining time
2. Reduce material costs
3. Reduce tooling costs
4. Reduce setup cost
Eventually increase VALUE of a product
Examples of design concepts
using Design For Machining
Limit Tooling
Bad Design – 2 different
techniques required
Better Design – profiles
similar
Radius Corners of Pockets
Extremely difficult, if
not impossible to
machine
Better Design
Chucking Surface
Poor Design:
No place for clamping
Better Design:
Area for clamping
Restricted Surfaces
Better Design:
Both areas now
accessible
Poor Design:
No access
Single Plane Clamping Surfaces
Poor Design:
Awkward and timeconsuming for clamping
Better Design:
3 surfaces for
clamping
Design For Assembly
Texas Instrument Example
Design For Assembly
Comparison - DFA
Original
Design
Assembly Time (h)
Redesign
DFA
Improvement
(%)
2.15
.33
84.7
Num. of Different Parts
24
8
66.7
Total Num. of Parts
47
12
74.5
Total Num. of Operations
58
13
77.6
Metal Fabrication Time (h)
12.63
3.65
71.1
.48
.26
45.8
Total Weight (lb.)
Comparison - DFA
vs.
TEAMWORK
Concurrent Product Design: Include ALL members
Team Makeup
• Basic understanding of teamwork in work
force environment
• Decision making techniques, ie.
Brainstorming, etc
• Project management skills
• Communication skills
• Problem resolution technique
Flowcharting
Gantt Charting
Communication Skills in
Teams
1. Listening skills: hearing and comprehending
what is said as opposed to waiting for one team
member to stop talking
2. Dialoguing skills: interacting for the purpose of
increasing mutual discussion
3. Consensus building: synergizing, building new
understanding as opposed to compromise
which is “both team members giving something
up” to arrive at a solution
Characteristics of
effective teams
• They produce results
• Purpose of the team is clear and takes priority over personal agendas
• Members feel invested in success and accountable for the outcome
• People are clear on their roles and assignments
• Nothing is under the table
• Team members are not afraid to surface a problem
• Trust, collaboration, and candid discussion are evident
• The team does not lose sight of its goal
Attributes of good team
members
• They have strong, shared values
• They overcome obstacles and handicaps
• They incorporate and represent diverse
backgrounds
• They are protective and supportive of one
another
• There is a submission of self for the good of
the team
CAD Systems
Spatial Skills
REVIEW
Who casts the biggest shadow in terms of
cost % in manufacturing?
Product Design
Explain how Design For Manufacturing is an
integral part of the product design cycle?
Review
• How can we add value to a product?
Reduce: Machine Time, material costs,
tooling costs, & setup costs
• Of the 3 communications skills, which do
you feel you can work on to improve ?
Why?
Listening, dialoguing, consensus