Screwdriver Project
Cast aluminum screwdriver
This cast aluminum flathead screwdriver started life as a blank, with a round shank and a cylindrical piece of aluminum. It was then faced and center drilled on a manual lathe. Following that, it was turned on a CNC lathe. Then, it returned to the manual mill for knurling. Then, the tip was drop forged and ground to create its flathead shape. Finally, the tip of the screwdriver was quenched and tempered, and sanded to 800 grit
injection molded screwdriver
This injection molded screwdriver was initially a phillips head shank and a few cups of plastic beads. The shank was placed in a mold, which was then placed in an injection molding machine, which injected molten plastic into the mold, filling it out in the shape of a screwdriver handle.
Lessons learned
Ensure you pay full attention and take thorough notes during the lab demonstrations, there are no process sheets so it is your only chance at getting the information you need to make the parts
Verify the screwdriver blank is placed correctly in the CNC lathe chuck so you save time when a TA or instructor comes to check your setup
Ensure both knurling wheels make contact with the screwdriver blank at the same time, such that both of them stop moving at the same time, to ensure an even, symmetrical knurling pattern.
When grinding the tip of the cast screwdriver, continuously use calipers or other measuring devices to verify the tip of the screwdriver stays within the specified tolerances
Use some scrap material to act as a pushbar to get an even, flat grind on the top and bottom of the screwdriver
Sand the shank of the screwdriver before quenching, after quenching, and after tempering
Ensure the injection molder for the screwdriver heats up fully and the plastic completely melts before injection molding
Cost estimate for one screwdriver
Efficiency Improvement proposal
The cast screwdriver process could become more efficient by using the CNC lathe to perform the knurling process
Using a more powerful drop forge could reduce the time spent forging
A CNC grinder could efficiently produce the ground tip of the screwdriver to tight tolerances, and create a fine surface finish to replace the sanding processes.