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March 1, 2004

6 Min Read
The Troubleshooter: Part 64: Reclaiming money earned


This article continues our series of troubleshooting reports from one of the leading on-the-spot problem solvers in the molding industry. Bob Hatch is manager of technical service and customer support for Prime Alliance, the Des Moines-based resin distributor. Before his present assignment, Bob managed a molding operation for 25 years.

Spend a little to optimize your mold; gain a lot over a year.

At some point during my seminars I get this question from someone in the audience: “Where do we get the money to pay for these tooling changes you have recommended?” For this reason, I always make sure the last page in my seminar handout is the Annual “Lost” Revenue per Molding Machine chart.

This chart covers machine rates from $30 to $100/hr and cycle time improvements from 10% to 50%. If you have faithfully followed the rules I have passed on to you in these articles, then you know you might have to pull your mold from the molding machine and take it to the toolroom.

You will always need to have the mold worked on for a few hours to correct normal problems in sprues, runners, gates, and vents. Whether you send out the mold to be worked on or handle it in-house, you need a few hours of a toolmaker’s time to optimize each mold.

Sometimes you need to buy components, like molding machine nozzles, heated sprue bushings, or differently sized quick disconnects for the waterlines. I imagine the total cost to optimize most molds is in the $500 to $1000 range. It’s seldom more than $500 from my experience, but that depends on how much has to be done to the mold. Sometimes all we need to do is add a little venting or change the gates a tad. But then we run into the occasional mold that needs everything in the flow path modified slightly.

I was in a shop the other day that had a lot of problems with cosmetics on an automotive part. Everything was sized correctly except for the gates; they weren’t deep enough and the gate lands were too long, causing sink on the part’s face that couldn’t be packed out. All they had to do was put the mold in the toolroom for an hour or so to fix the problem. This wouldn’t cost a lot of money and the simplest budget forecasting will cover changes like this.

On the other side of the coin, I remember not too long ago a shop I was in that needed to buy a new material dryer, replace the barrel and screw, and install a different hot runner system in the mold just to mold the parts without bubbles, moisture splay, shear splay, brown streaks, and black specks. This problem was going to cost a lot of money before they were done, especially since they would end up making the same corrections on at least six molding machines and on the molds running in these presses.

Optimize or Die

So where does the money come from? First of all, we should be putting aside some money for a rainy day. A good example of a rainy day for me is optimizing a mold that is running a lot of rejects in a slower-than-quoted cycle time. But I know it is sometimes difficult to set money aside, especially when profits are down thanks to those same rejects and slow cycles.

Once you start the process of optimizing your problem molds, you begin to realize higher profit margins than you imagined. My lost revenue chart is a good way to identify these extra profits. Once you have optimized a mold you see faster cycle times and a rapidly diminishing reject rate.

My experience tells me you will be able to speed up your cycle time by 25% to 30%. You have to be careful when you start cutting cycle time, though, because you don’t want to change any dimensions or cause warpage conditions on the parts; but if you have done everything according to the rules, brought the barrel heats down, and possibly increased the mold temperatures, then you should get the same dimensions and eliminate any warpage problems with the new process conditions.

I have been keeping track of the cycle time improvements I’ve seen over several years and find I am currently running at a 27.2-second average cycle time reduction. When I started out in molding, I was told by many experienced people that “if I was lucky” I might speed up a cycle by 1 or 2 seconds and even then, I might cause some serious dimensional problems. What I didn’t know then, and do know now, is that if you don’t bring down the barrel heats, you can’t make any significant changes in cycle times. It goes on from there: You can’t bring down the barrel heats if you don’t open up the restrictions to flow in the nozzle orifice, sprue, runner, and gate dimensions. It all comes back to the basics. This is why I have a page in my seminar book that says “If you always do what you have always done, you will always get what you always got!”

The Numbers Don’t Lie

Now, how do we read the lost revenue chart? Look at the left side of the chart, where it shows the percentage of cycle time improvement. If you understand and have followed the rules, you will usually get at least a 25% improvement in cycle time, so use this figure. To the right of 25%, find the hourly rate you are charging for your machine. The number in this box is what you will be able to earn additionally from this particular molding machine in the next 12 months. This scenario assumes that your newly optimized mold will be the only mold to run in this machine for the next year, or that every mold that will run in this machine has been optimized. The total savings for these molds will provide you with these additional earnings.

For example, let’s use the 25% cycle time improvement number and go across to the $50/hr machine rate. You can earn an extra $78,000 this year on this machine. If you have five $50/hr machines in your shop, all running optimized molds, you can earn five times that, or $390,000. You see how it adds up quickly.

This is where you get the extra money to buy nozzles and heated sprue bushings, and for the other mold work necessary to optimize problem molds.

Sometimes it is difficult for bookkeepers in the front office to see where the money comes from to invest in an optimization program. It’s not money that was given to you; it’s money that you’ve earned.

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