Machining an Aluminum Sand Casting Project
Here at Winn Mfg. we have been machining an aluminum sand casting project for a couple of years that has good volume. The project averages about 19,000 parts per year with three different castings and a total of six different configurations. One casting/style has a larger volume than the other (5) styles. My customer purchases 12,000 per year of that one style. When we originally took this project on, we tooled it up to be run on our larger CNC vertical machining center equipped with a pallet changer that has a 30″ X 20″ work envelope. The outside dimensions of castings are basically 7″ X 5″ X 5″ and have machining on three different planes. So the fixtures have three stations per pallet, so that one completed part comes off with each cycle. One of the reasons we put these parts on this machine was that it fit into the work envelope and we really didn’t have a lot of work for it at the time. The later reason was really the driving factor as to why we used this machine for this job.
Solving CNC Machining Bottle Necks
We have configured the fixtures and tooling so change over from one style to another was simple, but we were running into bottle necks when my customer needed some of the lower volume orders quickly, along with the higher volume main part. So we built more fixtures for the lower volume style parts and put them onto a CNC horizontal machining center that has a pallet changer on it. This helped, but the machine is an older machine and the rapids are not that quick, specifically the index table is slow, so the production suffered.
We also have a smaller CNC vertical machining center with a pallet changer; a Fanuc RoboDrill. We realized that the higher volume part would fit into the work envelope of this machine, but the lower volume castings are too large for the machine. There isn’t enough room with the Z-Axis because of the height of the parts. The larger parts are about 8.5 inches tall. This machine is not that new, but it is very fast. The rapids are over 1200″ per minute and the tool changer is quick, only a couple of seconds. Our production on the larger volume increased by 30%.
Since building the additional fixtures to run these parts on our RoboDrill, Winn Mfg. has purchased another CNC horizontal machine center with a pallet changer, that has faster rapids and a quicker tool changer. We have run the lower volume parts on this machine with very good production results.
The increase in production by moving this part to the RoboDrill has increased our profitability on the job, our turnaround time has decreased and it has allowed us to run the lower volume parts more efficiently on the larger Vertical machining center without sacrificing the production of the higher volume part. Also, we now have 2 options for the lower volume parts. This helps us with our throughput on both our CNC horizontal machines and on the larger CNC vertical machining center.
Spending Money to Make Money | CNC Machining
The main point of this blog has been to point out that you can’t get tunnel vision about a job and sometimes you have to commit to spending money on fixtures or tooling on an existing project in order to keep up with your customers needs and to keep a good job profitable. In this case, it was well worth the money spent for the additional fixtures.