Q.
We are going to purchase a new moulder and I have a couple of questions. Some moulders have jointing heads. I understand these moulders can run at speeds over 100 feet per minute. Would a machine like this be practical for a custom moulding business? Do these high speed moulders include longer setup times?
I'm thinking it would be overkill for a business that isn't focused on huge volume, but I want to achieve the best quality in our product. Could someone in the business fill me in on the differences between a jointing head moulder and a moulder such as Weinig's entry level moulder?
Forum Responses
I have 12 years experience with moulders and run both high speed and slower production. We use Wienig and Iida moulders. Jointing is great if you have long runs like 30 thousand and up. But it takes longer to grind tooling and longer set ups and of course it depends on the experience of the employee who runs it. For custom runs, I would have to say you'd be better off with a non-jointed machine to start with. But as you go with longer runs, go to a jointed machine.
With the extra time it takes to set up a jointed machine, you need to at least have a run of 5000 linear feet before it is feasible to consider running. A jointed head moulder is almost twice as expensive as a non-jointed machine and more complicated to set up.
A jointed head moulder requires you to be good at grinding your knives, because you have to grind a jointing stone that is the exact profile of the knife you are using and matches up with that knife at a precise angle. A jointed head machine, when it joints your knife, evens up the knives so that they are all the same. In this process you are actually dulling the end of your knife. You have to know how to grind. With a non-jointed machine, no matter how good you are at grinding, one knife is always going to be higher than the others. Even if it is only in the thousandths of an inch, only one knife (even though the other knives are cutting) is going to be cutting on the finish. In other words, the knife marks that you see on the finished product will be the result of the highest knife only.
With a Wienig non-jointed machine spinning at 6000 RPM, you can figure about 32 fpm. Plenty fast enough for manufacturing custom molding.
If the normal length of run is over 5,000 linear feet, a jointed moulder is worth looking into. It takes about twice as long to set up a jointed machine as it does a non-jointed one.
If your normal run is under 5,000 linear feet then a non-jointed machine is the one for you. In either case the tooling and grinding of that tooling is the most important part of the operation.
Without a doubt, attending a class is a good move. A wide number of machines can be seen and used at different schools. The more machines you get a chance to work on, the better it will be for you when making your decision.
Dave Rankin, forum technical advisor
Take special care of setting procedures together with tooling and grinding choices, since many false claims are made by some who do not have the technology in their machines.
I also have a hydramat 23--it is a 60m machine with a max feed rate of 180 fpm. I have run 1/4 x 3/4 scribe and 1 1/4 x 9" crown profiles. These were not all run at high speed but the versatility is a major advantage.
The concept of running a jointed machine is simple. The abiltiy to productively run high speed requires a top notch operator and extremely accurate tooling. Conventional runs are a lot more forgiving.
I agree with all the other statements on run lengths. I have made the break at 10,000' before I will consider a high speed run. The problem with a high speed run is competition. Large runs are normally high competition and low profit margin. I like the concept of Wienig's Unimat 23--I believe it's the yellow line. It's not a jointed machine but it does have higher rpm spindle rates which could give you a high quality finish at a good feed rate. Try to see the equipment in a productive operating environment.
As our customer base grew and the aging Diehl was down for frequent repairs, we knew we needed a new moulder. We had also learned a few lessons in buying a machine that was billed as "just as good as a Weinig only cheaper." Yeah right. Our response was to buy a new moulder.
We chose the Weinig Unimat 23 E with 6 heads. The layout of two top heads allows us to run wide/deep mouldings (as well as small and simple) with a very clean finish because you can profile with the first top head and leave .040" for the last top head to clean up. The Weinig we purchased also has some features that make it a dream to set up and run, short or long: Digi-set counters, the optical compariter "Opti-set", a must for the creative moulder operator that has to combine two different knives running opposite in a four-knife head to achieve the impossible demands of a boss who says "can we make this without making new templates?", and the "EM-11" auto feed. The auto feed can handle random lengths or run with all the same lengths with simple changes and allows the operator to spend more time at the outfeed end.
It's a cool machine that fit our nitch. I know that if our needs change our owners will choose another Weinig. The moral of the story--know what you want, buy what you need and never buy 2nd best.
P.S. With out a good quality profile grinder (and grinder operator) nothing else will matter.
Deep profiles: many European machines have a 200mm (approximately 7.75") cutting circle for the main profiling spindles. This design is based on the maximum knife extensions within European safety laws, and standard diameter tooling. One easy way to get increased cutting depths for deeper profiles is to have one or two heads with smaller diameter bodies (check with Charles Schmidt Co.), making sure they are the same hook angle as your other heads. These will allow you to grind deeper knives. Then, before grinding or regrinding, step the knife out four corrugations and grind as close to the head as possible--this will allow you to reset the ground knife to a smaller cutting circle before mounting in the moulder. A combination of smaller tool body and reset knife can give over 1/2 inch increase in depth of cut, yet keep in the same cutting circle.
