DM:- Medium Density Fibreboard, known as MDF in the trade. It is a type of hardboard made from wood fibres glued under heat and pressure, an alternative to plywood or chipboard. It is dense, flat, stiff, has no knots and is easily machined.
http://www.design-technology.org/mdf.htm

chapado: veneered (in case of wood ) or plated (in case of metal). Your translation will therefore depend on what follows in your text, eg. the MDF could be silver-plated (unlikely!) or walnut- or oak-veneered (more likely!).

You can see how the terms are used in the Spanish and English versions of the following webpage describing a table:

"Mesa rectangular. Estructura de DM chapado en roble color wengué. 1 sobre vidrio templado de 15 mm y un sobre de madera."
http://www.gautier.fr/es/collections/sejours/cocktails.html

"Rectangular table. Structure in wengé finish oak-veneered MDF. Top in 15 mm thick toughened glass over a wooden top."
http://www.gautier.fr/en/collections/sejours/cocktails.html