D. Surface Finishes Required:
Certain textures will hide or disguise molding flaws such as surface scratches, minor imperfections in radii, flow marks, etc. However, many of the lighter textures such as MT 11000, MT 11010, MT 1055-2, etc. are very subtle and shallow, and their fine grained character are not designed to hide these types of imperfections in either the cavity or in the resultant molded part.
Texture finishes in general require a basic minimum of a 240 stone finish. That finish will suffice for most patterns that finish at a depth of .0025" or deeper.
When your texture needs are for finer depth patterns, such as those noted above or their equivalents, which finish at .0015"or less, we advise that you finish the surface of the mold to 400 emery paper or SPI B2. Although a 240 stone finish may seem smooth enough, it often leaves behind minute surface scratches that may show up through a fine texture once the process is complete. Once those scratches show through, repairing them is difficult, so it is much more expedient to ensure the surface finish is fine enough before texturing begins. It is our practice to alert a customer that they may require a better finish before texturing when we receive the mold and inspect it, and note that the finish is a bit rough for the pattern chosen, so think of us as a second line of defense in your quest for quality.
On rolls that require texture, a minimum recommended surface finish is a # 32 Microfinish. This is important, since the fine striations often seen once a roll has been on a lathe can be visible after texturing. These striations are not visible in a # 32 Microfinish.
Regarding the MT 1055 / Series ¡¯93 Plaque, the reverse side of the plaque contains a number of "Microfinishes" ( not to be confused with the "Microfinish" noted above ), which are numbered from MT 11001 to MT 11007. The successful applications of these finishes requires some basic minimums : they are designed for P20 steel and we cannot guarantee identical results in any other steel for these particular patterns; and a pre-texture finish of SPI A2 is essential. These finishes are so subtle that any finish rougher than an SPI A2 will distort the texture appearance to an unacceptable level for most applications for which these textures were designed.
If you have any questions regarding surface finishing pre-texturing, please call us.