Sanding Equipment for a Finishing Shop

A high-quality wide-belt sander can consistently thickness-sand MDF parts, and also sand primer coats, efficiently in a production environment. July 3, 2008

Question
We're experiencing a bottleneck in our finishing operation related to sanding. We spray prime approximately 800 sq ft of MDF per week with a water based millwork primer. We're currently hand sanding the faces of our parts with small random orbit sanders (moulding profiles are sanded by a spindle sander). We typically prime once and sand with 180 followed by a light spray touchup where required. This results in a very nice primed finish on the face of the parts. The face width of our parts can vary from 3" - 30", length between 18" - 97".

We're thinking a very important issue is the thickness tolerance of the MDF we use. It's a name brand Canadian ultra light board, but can vary +/- 0.005" in thickness, mostly between units. Often we have parts in the same production run that differ in thickness.

We'd really like to reduce the time spent hand sanding and improve the consistency of the product. We're not well versed in wide belt or stroke sander operation. I'm hoping to get some insight on the following...

1) Should we be looking for a wide belt with platen? Can a machine like this hold a very small tolerance?

2) A stroke sander perhaps? Never used one.

3) We have a Performax 37 and we've considering one of their brush heads. At first glance the conversion seemed pricey and we're not thrilled with the machine to begin with.

Forum Responses
(Finishing Forum)
From contributor C:
At OSF we had many Timesavers that we used for this purpose. What we did is run the MDF through the dual-head sander first to make sure the uneven thickness was not an issue. Once that was accomplished, then it could safely be primed, sealed, etc. knowing we would not cut through the primer.

The Timesavers are expensive, but if you can budget it, it's well worth the money. It is adjustable down to .001 inches (1 mil), so if you're putting 2 or 3 dry mils on, you should not cut through the primer coats. We had others set up for urethane and polyester needs also. In my opinion, if you're going to be continuing in this fashion, it would be a sound choice to make, especially if you're a growing company and are going to continue to grow in your finishing/sanding needs.

A stroke sander would be my very, very last choice for this work.



From contributor R:
A Makor profile sander is the way to go if you can afford it.

From contributor C:
For profile work I would agree with contributor R.

From contributor R:
For flat stock the Heeseman wide belt does a great job scuff sanding. If it is set up right, and you have a good guy running it, sand-throughs should be pretty rare. However, if your MDF is varied in thickness, you would have to sand it all to the same thickness first or buy better quality MDF.

From the original questioner:
Thank you all for your responses. Contributor C, regarding thickness sizing of MDF through a wide belt... You mentioned using a dual drum unit. Would that be two top drums or 1 top/1 bottom? From your experience could I get by with a single drum unit or are 2 drums required for sizing?

Another sander type I forgot to include in this discussion would be a fladder type sander. Do you have any experience with fladder type sanders? I'm not sure of the precision of a fladder type unit and wonder about the softening of molding profiles when parts are run through.


From contributor C:
Sure, you could use a single head no problem. That's just what we had. Timesaver has smaller units also instead of the 50" which are less expensive, but I'm not up on the pricing. Fladders are more of a surface conditioning machine rather than a means of uniformly flat sanding, meaning they will smooth the surface but not as evenly as a wide belt, so that would be up to you. As suggested, there are other wide belts out there besides Timesaver, but the most important thing in your case is the ability to sand in increments of >001". As long as the machine can accomplish that, it will work for your needs - though I think Timesaver is easier to use than most.

From the original questioner:
Looks like we'll be searching for a wide belt then! Thank you for your input - it's been most helpful.

From contributor C:
One other note: we were using all solvent base products, not water. Contributor R might be able to answer this more surely, but you need to test run your finish on the machine of choice as to how it will sand your primer before you plop down the money for purchase. You may find, though I'm not sure, that your waterbase primer clogs the belts faster than conventional solvent primer. Do test to assure this is not the case! Run the test with panels dried to the same stage you normally start your DA work now just to make sure this will not be an issue. Belts are expensive and you don't want to find out too late you're going through them faster than you would with a typical solvent primer.
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