Machining MDF

Tips for machining MDF. 1998.

by Professor Gene Wengert

I am presently preparing a bid for some raised panel wainscote. The final finish will be painted white and I am thinking about using MDF for all components panels, stiles, rails, etc. in place of poplar. I have used MDF mouldings in the past and my client does not have a preference for solid wood vs. MDF. What I need to know is if the standard shaper cutters I presently use for solid wood will machine the MDF in a similar fashion and also any tips that you may have for achieving a quality job; cutter speed, feed rate, sanding, etc.

I do not have much expertise in this area--I have experience with "real, solid" wood and not composites! But, I can share with a comment or two.

First, always machine composites aggressively--if you are feeding too slowly, you will get a lot of rubbing, subsequent heating, and rapid tool dulling. With dulling comes more heating, and essentially impossible, intolerable results (quality).

Second, (not with MDF) we are always concerned about the amount of ash in particleboard--ash comes from debris during accumulation and manfacturing of the chips. High ash content means instant dulling of the tools, etc.

I would suggest that carbide or stellite tooling is essential.

Contact Sandy Stewart at Mississippi State University's Forest Products Lab for more information. He is the top machining researcher, especially with respect to tool dulling. He adds the theory to what we know from experience.

Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison.

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