Case 1: Mounting of electric boards
Current situation; screw fastening
An operator grabs a product part and the electrical board which has to be mounted on the part, places it on the mounting table and positions the two parts. The operator mounts the electrical board with 5 screws and removes the assembled product. Due to the use of an electric screwdriver, the following table describes the assembly process:
| Activity | Inlay, positioning | 5 mounting points | Removal |
|---|---|---|---|
| Parts | Base plate, electrical board | 5 screws, electrical screwdriver | Assembled product |
| Process time | 10 sec. | 50 sec. | 5 sec. |
Conclusion
Assembly time is 65 seconds per electric board. In 6 hours effective operating time 332 products are assembled a day. In a year this comes to 66.461 products, the cost of labour per product is +/- 0.45 euro with 30.000 euro annual labour costs per operator.
New situation; CNC riveting
An operator grabs 5 product parts and 5 electrical boards which has to be mounted on the 5 parts, places it on the indexed turntable and positions these parts. Pressing the start button, the CNC Riveting machine will turn the table a 180 degrees and starts riveting. In the mean time the operator removes the assembled products and places the new parts and presses the button again. Now the following table will describe the assembly process:
| Activity | Inlay, positioning | Automatic Riveting | Removal |
|---|---|---|---|
| Parts | 5 Base plates, 5 electrical boards | 25 rivets, CNC controlled | Assembled products |
| Process time | 50 sec. | - | 25 sec. |
Conclusion
Assembly time is 75 seconds per 5 electric boards, 15 seconds for one board. In 6 hours effective operating time 1440 products are assembled a day. In a year this adds up to 288.000 products, the cost of labour per product is +/- 0.10 euro with 30.000 euro annual labour costs per operator.
Return on Investment
In order to calculate the R.O.I. we take into account:
- Cost price screw = Cost price rivet
- Energy consumption of the riveting machine is negligible
- Necessary investment CNC riveting machine = 65.000 euro
- No extra investments are necessary to install the riveting machine.
- Cost savings on labour, due to the use of a CNC Riveting machine = 0.35 euro(= 0,45 - 0,10) per product.
| Production a year | 50.000 products | 150.000 products | 288.000 products |
|---|---|---|---|
| Cost savings on labour per year | 17.500 euro | 52.500 euro | 100.800 euro |
| Investment costs CNC Riveting machine | 65.000 euro | 65.000 euro | 65.000 euro |
| R.O.I. in: | 44 months | 15 months | 8 months |