Introduction to Design Manufacture & Assembly (DFMA/DFA/DFM)

BMFR 4152: Design Case Studies (Concurrent

Engineering)Week 1Taufik

Product Development Process

Introduction DFA Guideline 1. Reduce number of parts 2. Reduce number of different parts - Standardize parts 3. Simplification of assembly 4. Reduction number of processes 5. Less fasteners especially screws & bolts 6. Reduce tangling 7. Orientation 1. Critical orientation – obvious – see & fit 2. Non-critical orientation – fit in any direction 8. Ensure access & visibility 9. Easy part handling 10. Assemble from top 11. Reduce locating/alignment operations – manual/time consuming

Reduce Number of Different Part – Standardize Parts

I. One Time Costs Tooling Design/Development Contacting / Vendor Selection Product Testing

II. Continuous Costs Material Assembly Inventory Inspection

Simplification of Assembly Easier = faster Less opportunity for mistakes Easier to automate

Reduction Number of Processes

Less steps = faster Less material handling = less

damage Less operations = less opportunity

for defects

Case 1

Case 2:Motor

Drive

The Impacts of DFMA Less parts to design, document, revise Less Bill of Material (BOM) cost, parts to receive,

inspect, store, handle Less labor and energy to build product Gets into the customer’s hands faster Less complexity Simpler assembly instructions Higher quality Higher profit margin More competitive in the marketplace

The Advantages of DFMA Quantitative method to assess design Communication tool with other engineering disciplines and

other departments (Sales, etc.) Greater role for other groups while still in the “engineering”

phase such as Manufacturing Since almost 75% of the product cost is determined in the

“engineering” phase, it gives a tool to attack those hidden waste areas before committing to a design

Fact: Fasteners typically account for 5% of BOM cost, yet contribute to 70% of the labor cost!

Flowchart for DFMA

Case 3

DFMA- Waste of Complexity The goal is to achieve simple solutions in place

of complex ones Complex solutions tend to produce more waste

and are harder for people to manage Waste can take the form of time, energy,

labor, defective production, etc.

In our case, replace “solution” with “design”

DFMA-Design Guidelines Design for top down assembly Make parts self locating Try to design parts with symmetry If symmetry is not possible then make it obvious that

the part needs a specific orientation Prevent stacked parts from getting stuck together or

tangled using features Avoid parts that are difficult to handle, i.e. too small,

sharp, fragile, etc. Avoid parts that only connect. Try and bring the other

parts together to eliminate the connection Avoid adjustments. In general, adjustments

compensate for poor design

Procedures of The Analysis of Manually Assembled Products

STEP 1. Obtain the best information about the product or assembly; useful items are:

engineering drawings exploded 3-D views existing version of the product [for a redesign] a prototype

STEP 2. Imagine how the assembly would be dismantled, or for a redesign do it with an actual part.

If the assembly contains subassemblies, treat these as parts first.

STEP 3. Set up a worksheet with cells for appropriate entries part name, number of parts, theoretical part count, handling time, insertion time, assembly time, assembly cost

STEP 4. Begin assembling, or re-assembling the product.