This document summarizes a design for assembly analysis of an electric razor: 1) The original razor design consisted of 14 parts that were assembled using screws, requiring over 90 seconds of assembly time. 2) Recommended modifications included integrating snap fittings to replace screws, simplifying symmetrical parts, and reducing the total part count. 3) The redesigned razor required only 11 parts and took under 50 seconds to assemble, improving the design efficiency by over 30 percentage points.

1. Design for assembly analysis
of Electric Razor
COMPUTER
INTEGRATED
MANUFACTURING
INDU 411
WINTER 2012

2. The Product
 Wahl 2AA battery powered electric razor,
model 9906
 Low cost
 Simple design

3. Exploded Assembly view

4. DFA Analysis
1 2 3 4 5 6 7 8 9 Name of Assembly
manual insertion time per
Manual handling time per
Figures for estimation of
2-digit manual insertion
2-digit manual handling
Operation cost in cents
operation is carried out
theoretical minimum
Operation time in
Part ID Number
No. of times the
consecutively
seconds
parts
code
code
part
part
WAHL 9906 Razor
1 1 00 1.13 00 1.50 2.63 1.052 1 Plastic base
2 1 30 1.95 30 2.00 3.95 1.58 1 Motor
3 1 35 2.73 30 2.00 4.73 1.892 1 Small metal battery clip
4 1 30 1.95 30 2.00 3.95 1.58 1 Large metal battery clip
5 1 30 1.95 31 5.00 6.95 2.78 1 Power switch
6 1 35 2.73 02 2.50 5.23 2.092 1 Spring
7 1 30 1.95 30 2.00 3.95 1.58 1 Plastic top base
8 2 11 1.80 38 6.00 15.6 6.24 0 Base screws
9 1 30 1.95 31 5.00 6.95 2.78 0 Plastic cover
10 1 30 1.95 30 2.00 3.95 1.58 1 Battery cover
11 1 31 2.25 02 2.50 4.75 1.9 1 Plastic blade holder
12 1 33 2.51 00 1.50 4.01 1.604 1 Lower blade
13 1 33 2.51 00 1.50 4.01 1.604 1 Upper blade
14 2 16 2.57 39 8.00 21.14 8.456 0 Blade screws
TM CM NM Design Efficiency =
91.8 36.72 11 0.359477124

5. Recommended
Modifications
 Top razor assembly
 Bottom assembly and screw covers
 Spring
 Plastic piece for razor assembly
 Small battery terminal

6. Bottom Assembly
BEFORE AFTER

7. Top Assembly
BEFORE AFTER

8. Razor Assembly
BEFORE AFTER

9. Plastic piece for razor assembly
BEFORE AFTER

10. Small battery terminal
BEFORE AFTER

11. Spring
BEFORE AFTER

12. DFA After product modifications
1 2 3 4 5 6 7 8 9 Name of Assembly
2-digit manual handling
2-digit manual insertion
Part ID Number
code
code
part
part
Manual handling time per
manual insertion time per
Operation time in seconds
theoretical minimum parts
No. of times the operation
Figures for estimation of
Operation cost in cents
consecutively
is carried out
WAHL 9906 Razor
1 1 00 1.13 00 1.50 2.63 1.052 1 Plastic base
2 1 30 1.95 30 2.00 3.95 1.58 1 Motor
3 1 30 1.95 30 2.00 3.95 1.58 1 Small metal battery clip
4 1 30 1.95 30 2.00 3.95 1.58 1 Large metal battery clip
5 1 30 1.95 31 5.00 6.95 2.78 1 Power switch
6 1 35 2.73 00 1.50 4.23 1.692 1 Spring
7 1 30 1.95 30 2.00 3.95 1.58 1 Plastic top base
8 1 30 1.95 30 2.00 3.95 1.58 1 Battery cover
9 1 21 2.10 02 2.50 4.6 1.84 1 Plastic blade holder
10 1 33 2.51 00 1.50 4.01 1.604 1 Lower blade
11 1 33 2.51 31 5.00 7.51 3.004 1 Upper blade
TM CM NM Design Efficiency =
49.68 19.872 11 0.664251208

13. Results
 Elimination of screws (4 total)
 Elimination of plastic screw cover
 Reduced part count
 Reduced assembly time by 42 seconds
 Increase in 30.48 percentage points efficiency

14. Conclusions
 Drastic improvements
 Small changes
 Adding snap on features
 Symmetrical features
 Reduce the total part count
 Made the assembly an easier process