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.
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.
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.