Injection molding is a fully automated, high-volume process usually requiring thousands of parts at a minimum. If you want to do any activity, you need to “get your head in the game,” as coaches continually say in post-game interviews.
Start out thinking this way:
- It is unacceptable to run anything less than full cavitation.
- Filling all cavities at the same rate is mandatory.
- There is no excuse for poorly functioning molds and equipment—preventive maintenance is always more profitable than repairing a breakdown.
- Machines are always cheaper and more reliable than people. You’d be amazed what you can do with a sprue picker with a little creativity. Full automation inside the molding machine gives consistent cycles, higher yields and increased profits.
Molding is all about profits. Asking a few innocent questions will point you to where you need to put your efforts. The technique is a Pareto chart: Look at all your jobs for the past few months. Draw up a chart showing what each purchase order really cost you (including the re-runs for rejects, etc.). Make a bar chart showing the actual profit per 1000 parts. Keep in mind that losing money on small jobs is still lost money, even if the large jobs make a high profit.
Applying the 80/20 Pareto principle works out to 80% of the money lost comes from 20% of the jobs. Now you know where to start looking!
Looking only at your “losers” makes up another Pareto chart. This time, as a group, find out where you’re losing money:
- Higher material costs you couldn’t pass on to the customer.
- Longer cycles you couldn’t pass on to the customer.
- Poor yields.
- Molds or machines in need of maintenance.
- Longer than budgeted setup/change-over times.
Let’s look at each item.
Material costs. This is a cost you have no control over. Many buyers play the game of saying they only adjust the material cost once or twice a year. Each time you get a purchase order for parts, look at the current cost of resin. If the material cost is out of … .
