Building a Mold: The Importance of Grinding

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Most rubber mold components begin as a steel plate. Apple Rubber purchases these steel plates in a somewhat unfinished state. They are either machined or Blanchard ground to our specifications.

Take a closer look at machined and Blanchard ground steel below.

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Machined finish steel。 Face mill markings are evident。

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Blanchard ground finish. 


While acceptable for some applications, machined and Blanchard ground finishes are often not smooth enough and do not produce an acceptable thickness, flatness or parallelism for rubber molds。 For rubber molding applications, precision surface grinders are the best choice to achieve the surface finish you need。 

Precision Surface Grinding

Apple Rubber uses precision surface grinding to obtain the tight tolerances that are required for rubber molds. Precision surface grinding uses an abrasive wheel that rotates and is brought into contact with the mold component. The mold component is then moved back and forth until the entire surface has been ground. The process can be repeated until the work piece meets specification. Very fine surface finishes and very tight tolerances can be produced, which can be altered depending on the specific type of wheel and grinding parameters used. 

Our mold making facility has several different automatic and manual surface grinders。 Each grinder is equipped for general surface grinding as well as specific uses, such as grinding non-magnetic materials like aluminum and insulation board, grinding pins and cores to height and efficiently grinding large numbers of small, thin mold components。 Specialized mold making requires specific work holding, fixtures, grinding wheels, training and experience。

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This is an example of a machined plate being surface ground. The surface grinding operation is removing the machine marks and making the plate more flat and parallel. 

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Finished mold plate after surface grinding.

Our mold shop is key for producing quicker lead times on o-rings, gaskets and custom molded shapes。   With proper grinding techniques, we can provide the high-quality parts our customers deserve。