THE COASTER
The coaster is an aluminum bar stock that is cut to size and run through a CNC program to make the desired shape.
WHAT I LEARNED
While the forging of the screwdriver was my favorite, the CNC mill impressed me the most. We took the HASS certification exam, which was about 45 minutes, and before I was even done, I had a part in my hands that I couldn't even dream of making manually. I Learned that CNC can produce extremely complex parts in the blink of an eye but requires more knowledge and certification to use then the rest of the processes. given the expensive nature of the machines, and the fact that they probably produce a different part every day, it's important to have a vigilant operator, and cant easily be automated.
TIPS FOR THE NEXT STUDENTS
watch others take the HASS exam beforehand, it gives you a good idea of what you might miss.
Take lots of notes on the online HASS lectures and spend time with the machine in person to help visualize what those notes mean.
COST OF MAUFACTURING BY HAND
Assuming the machines required to make the parts are all accessible, let's look at how much it would cost to make the coaster by hand.
(cost rounded to nearest Doller)
(stock priced at McMaster-Carr)
4' x .5' x 1ft aluminum bar stock cost: $6
cost of labor: $28 / hour
time spent in CNC: 30 min
time spent modeling: 30 min
total cost: $34
if you're caught up on the costs of the other parts, you'll know this is exponentially lower than the cost of the other hand made projects. This is because CNC is something of an automation in itself. It changes the tools, cuts the piece, and adjusts the feed and speeds all at the push of a button. one could argue that the coding itself will rack up the price. but most modeling Sofware will write the G code for you. Regardless, let's see how we can make this even cheaper by looking at automation and mass production.
COST OF MANUFACTURING 10000
Once again, as we were previously only making one part, we wanted to buy the smallest stock that could still make our piece, so we weren't wasting money. Now we can buy our stock in bulk which will cut the costs. This part is rather complex, and CNC truly seems to be the right machine for the job, so how can we automate that? let's say we have a facility with 20 CNC mill. we can set up the robot arms we saw from the sheet metal lecture, and set a large pile of bar stock next to them. The robot will be programmed to place the raw stock, tighten the vice, clean off the mill when a part is finished, and repeat. The robot will also use AI to detect of something goes wrong and will stop the machine. To verify it's all working well, a human operator will watch the first round and inspect the part before letting it fully run. When stock gets low or the pile of coasters gets too high, workers will move the complete parts to a storage facility or fill them up with more stock.
So, let's see the cost.
Coster width: 3.15' (on both sides)
3.15 x 10,000 = 31500 inches / 12 =2625 ft
Cost for 6ft of bar stock: $27
2625/6 =438 bars x $27 = $11,813
total cost: $11,813
Cost per unit = $11,813 / 10,000 = $1.18 per part
that's over 30 times cheaper! While the CNC is already a manufacturing marvel. Cutting down on labor costs with automation makes it that much more cost efficient. That being said, the major benefit of the CNC machine is its ability to produce almost any part by putting some stock in the vice and plugging in a USB with some G code. This lends the CNC to be effective in both high variance low quantity and low variance high quantity.