Lessons Learned

I probably had the most fun with the screw driver project, and I’d say this is probably the closest I will get to blacksmithing in my life. I really enjoyed closed die forging, learning how to heat treat and harden the screw driver and overall, this project was just a very cool and different project to the rest. I learned about how molds and dies works, how injection molding works and not just how to harden steal but also what’s happening on an atomic level in the steal to change its properties. For future students my advice surrounding this project is to take your time setting up the knurling tool on the lathe. This is something that I struggled with and it just takes that extra attention and work to align the wheels perfectly and avoid uneven knurling. The other thing ill say is to avoid hesitating when your heat treating the tip, the tip will start to heat up quite quickly towards the end and its important to get it into the water as fast as you see that straw color on the tip.

Cost Estimate

• Raw Materials
  • Cast aluminum handle
    • Length: 4.5in
    • Diameter: 1in
    • Cost for $3.50/lb => $1.20
  • Steel Shaft
    • Length: 3.5in
    • Diameter: 1in
    • Cost at $2.00/lb => $0.20
  • Casting $.2 per blank .083 hours
  • Labor
    • Handle Turning/Knurling 0.35 hours
    • Forging 0.25 hours
    • Grinding .25 hours
    • heat treating .25 hours
    • finishing .1 hours
    • Average U.S. hourly manufacturing shop rate $80/hour
• Total cost: $104.24
• Total Time: 1.283 hours

Efficiency Improvement Proposal

We could avoid manually facing or CNC cutting the final handle and instead just die cast the final handle shape and dimensions. This would save material, time, and tooling. We could also grind the forged screw driver tip using a CNC grinder to save time and cut down on labor. final we could do all of the operations in large batches cutting down on time between operations and improving efficiency and consistency. The most extreme but effect approach would also involve completely automating the process. These improvement could be implemented either individually or all together and would drastically decrease the labor hours, the biggest expense to produce the screw driver. It would also accelerate the process increasing the possibly production quantity.

Mass Production Cost Estimate

• Manual EMEC Production cost of 10,000 units
  • Material cost: 10,000* $1.4
  • Tooling & fixture cost about $5,000
• Total cost: $19,000
  • per unit: 1.90

• Automated Production
  • Die cast aluminum handle: $1.50 * 10,000
  • Steel Shaft $0.2 *10,000
  • Tooling $5,000
  • Total cost: $22,000
    • cost per unit: $2.20

The Automated Process is more expensive if you do not account for labor because of the die cast handles which are much faster and cheaper to produce once you account for the time required and material wasted to produce the Manual EMEC Production version.