W1 Des for Manuf Assembly DFA DFM
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Introduction to Design Manufacture & Assembly (DFMA/DFA/DFM)BMFR 4152: Design Case Studies (Concurrent Engineering) Week 1 Taufik
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 PartsI. One Time Costs
Tooling Design/Development Contacting / Vendor Selection Product TestingMaterial Assembly Inventory Inspection
II. Continuous Costs
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 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 customers 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
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
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.