Quick Mold Change

By joeprocess
Published: May 18th, 2010

What is the number one most cost effective solution to improving QMC?

Out of the variety of different QMC clamping systems, what works and what doesn't?

That was a very enlightening

That was a very enlightening write-up about QMC and some very valid points to keep in mind before we even start to go near a QMC system!! I doubt whether we’ll get such advice and suggestions even from someone who is known to us and I must say that he has taken a lot of patience and time to write such an elaborate explanation and the importance of training before you really get down to the most effective quick QMC system!!

www.burco-molding.com

Joe, Rick and anybody

Joe, Rick and anybody else.

The more I thought about it, the less this fits into a simple topic comment - my original post was actually way too long anyway.

The real answer is to do a study. There are a lot of things to consider before jumping into the quick change business. I've put it together in an article either IMM will publish or it will show up on my website. If you want an early peak and how to go about this, send me an e-mail.

Put in the subject line "QUICK CHANGE" so I can tell you're not a Nigerian Prince asking my help with an inheritance or you've got a pill to enhance my romantic ability.

Bill Tobin
bill4012@hotmail.com

I see a few items that must

I see a few items that must be addressed BEFORE you go to a QMC system. 1-Water must be standardized on every mold and every machine. No exceptions. 2-Mold plates must be standardized based on machine platten sizes. This allows you to run bolts through the plates for fast mold mounting, or the plates can have slots that fit more platten sizes. Either way you have a faster change over and the bolt lengths can be standardized. 3-Ejector rods must be standardized.
Now I have worked on Engels' QMC system, and love it for any size press. You can still bolt molds in if need be! I have experience now with magnetic (Tecnomagnete) systems, and love them. Their only drawbacks are no insulator boards on the molds (you can place them between the mold and clamping plate) and you lose some clamp stroke/day light due to the plate thickness, often times requiring a nozzle extension. Some molds may require an additional plate to cover enough magnetic poles for safety, but if you refer to item #2, this is a moot point! I have seen the clamping wedges and such, no experience but they seem OK. Now, I have changed a 2,000t wheel house mold, from part to part with another good tech in 30 minutes: part to part but no preheat station and no resin change. Here, we can change a 600t even faster with no resin change. So Bill, as usual, makes some other very valid points. I hope this helps, Rick.

Thanks Bill, you make a lot

Thanks Bill, you make a lot of good points. But, if you were efficient in many of these areas or getting there and platen clamping, was the next logical step, what would you go with? Would you suggest any of the clamping systems, more labor, team mold changes, more tools, more supplies, manifolds on all molds?

The fastest and most

The fastest and most effective quick change system interestingly enough is TRAINING.

I did a study of a few companies who had these systems: Without naming names and with no disrespect to the guys who sell these, here’s what they were

1. the system used standard sized plates (about 2-3 inches thick) that was mounted to the clamping side of all molds. Every mold was now a standard size from a clamping point of view. They had permanently mounted rollers on both platens. You put the mold on the rollers and pushed it into some stops. Result was a centered level mold. If you were sexy, you also had oversized hydraulic clamps than neatly snapped over the plates.

2. The platens were drilled with tapered holes about 2” in diameter. Each mold had four pegs with the same taper (kinda like LONG die locks). You put the pegs into the holes, closed up and then clamped it. This system is adaptable to any size mold because the holes and the pegs are in fixed positions.

3. The platens are machined with a series of large “T” Slots positioned horizontally and vertically. In each slot is a screw drive. On each drive is a hydraulically actuated clamp. You mount the mold, turn on the screw drives and when they hit the clamp plate, the clamps lock into position.

4. There are two permanent magnetic plates mounted to the platen. You mount and center the mold, activate the magnets and Viola` no clamps!

When looking at quick change systems the problem ISN’T how fast you can mount the mold. The appropriate metric is the time from the last part being produced to the first part of the next run being produced,.

Quick change systems only allow the mold to be mounted faster. What they don’t tell you when you commit to these systems is what a truly quick change systems requires:
-- The waterlines are manifolded into a 1-In /1-Out connection for each side (this also means balancing all the circuits on the mold’s manifold.}
-- The mold is brought up to temp before you hang it (requiring some spiffy planning, extra hookups and blah, blah. }
-- If you have a hot runner system, this too must be preheated.
-- The setup team, cranes and mold are available when you need them (and haven’t we all seen this problem?).
-- Material changes require portable Master dryer hoppers and mini-hoppers on the machine. The new material is pre-dried and stationed near the press before the mold hang is begun. You pull off the mini hopper from the prior run, pop in purging compound and let it cook, hang the mold, put in the new mini-hopper and with a few purges you’re ready to run. Again this assumes you are processing materials with similar melt points. Going from PEEK to LDPE or the other way around takes time for the barrel temperatures to normalize and not cremate the low temperature material during the changeover.

The study I did found that with a well trained team (two people only for the initial hang, one person for the material change/startup), who had the right equipment, with a pre-watered mold (no hunting expeditions for water lines), knock out rods and such with the mold, lifting equipment available, material staged etc. the money and gadgetry of a quick change system really didn’t buy you anything.

All things being available, up to a 500 Ton machine you can go part to part in less than an hour. I’ve seen up to 1500 Ton machines done in less than two hours. To be fair, accounting for Murphy’s laws, because the setup team is routinely pulled away for troubleshooting, lunch breaks, hunting for knock out rods and hoses, finding shorted electrical circuits in the hot runner systems, even something as silly as not being able to find enough safety hoist rings, I’ve seen large machines take days to set and smaller machines take an entire shift.

If you’re going to spend anything to shorten changeover times do this:

Get a video cam and a tripod. Record your team changing a mold. The go back and look at what they did: Then start asking questions:
-- How many trips were taken to find the proper torque wrenches, etc?
-- Why did walk away from the setup (to spell relief operators? Coffee breaks, Troubleshoot a running machine? Bathroom/lunch breaks?)
-- Why did the machine have to sit idle for 4 hours while the material dried?
-- Why did it take several hours to get a good part (lack of a Universal Setup Guide)?
-- Why was the machine ready but production didn't start? We've all had this lame excuse also(lack of operator, no packaging materials for this part, no flash knives, screw drivers, secondary equipment, no tape machine to build the boxes etc. Having the proper labels would be nice, packaging instructions and skids to put the boxes on complete with stacking instructions.

Fix the problems, not the blame.

If quick change systems were so good, the machine manufacturers would have them pre-installed as a competitive sales feature. The fact that they don’t even offer it as an option (with the exception of the peg-and-hole guys – Where you can buy the machine with the holes in the platen but don’t necessarily have to mount the pegs on the mold) should tell you what the industry thinks of the effectiveness of these systems.

While I have nothing against these systems, you first have to start with the very efficient changeover before you start looking at cutting time in the mold hang/mold pull portion of a setup. I’ve watched really sharp guys who didn’t have to change materials go from part to part is 15 minutes. I’ve only seen one company who does this routinely; but they do 100+ mold changes a day and they are flummoxed if any mold has to run more than 200 parts. And before you ask, they run machines this way from 75 tons to as high as 750 tons with a library of 300+ materials. BUT they specialize in short runs.

I hope this helps.

Bill Tobin

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