Chapter 23 



FACE EMBOSSED HARDBOARD 



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MOLDED HARDBOARD 



Figure 23-95.— (Top) Face embossed hardboard. (Bottom) Molded hardboard. (Draw- 

 ing from Suchsland and Woodson 1985.) 



indicate standard wall stud spacing of 16 inches. The score marks can be 

 machined with saws or fixed scoring knives. From the first-pass trimmer, boards 

 are transferred to a cross trimmer which cuts panels to length. Such a trimmer 

 combination might process 7,000 4- by 16-foot panels in 8 hours. End saws 

 (with breaker heads to hog trim waste) might typically last 40,000 to 50,000 cuts 

 before dulling; center saws, cutterheads for rounding edges, and scoring saws 

 must be exchanged every 4,000 or 5,000 cuts. 



Punching. — Perforated hardboard (pegboard) is manufactured '/s-inch thick 

 with 3/16-inch holes, and lA-inch thick with 9/32-inch-diameter holes, for use 

 with matching hooks designed to support tools and other hardware in verical 

 array. The holes are sheared by overhead cylindrical punches moving through 

 holes in an upper clamp plate into bushings in a bed plate below the board. The 

 withdrawal (up) stroke requires more power than the cutting stroke, tends to pull 

 boards up, and to cause deformations of top board surfaces adjacent to holes. 

 The decorative side of the hardboard is therefore turned down in the punch press. 



Face embossing. — Embossing, in which certain portions of the mat are 

 compressed more than others to simulate textures such as sawn or weathered 

 wood and stone or brick walls, is accomplished during hot pressing by use of a 

 profiled top caul (fig. 23-95 top). Depth of face embossing is limited by a 

 maximum density under the embossed portion of the board (65 to 70 pounds/cu 

 ft) above which blistering will occur. For wear resistance, low-density portions 

 of embossed boards should weigh at least 40 to 41 pounds/cu ft. Embossing 

 patterns on 1/4-inch-thick hardboard typically do not exceed a 1/10-inch; on V%- 

 inch boards patterns are shallower. Embossed boards are generally surface 



