SPI Mold Unit Insert Standards

CLASS 1 UNIT INSERT

1. Detailed mold design required.
2. Insert retainer to be uniform hardness of at least 280 BHN.
3. All molding and/or functional details are to be made of tool steel hardened to at least 48
R/C.
4. Slides must have wear plates.
5. Temperature control provisions to be in cavities, cores and slides wherever possible.
6. Over the life of a mold, corrosion in the cooling channels decreases cooling efficiency
thus degrading part quality and increasing cycle time. It is therefore recommended that
plates or inserts containing cooling channels be of a corrosive resistant material or treated
to prevent corrosion.
7. Parting line locks are required to be on all molds.
8. Insert retainers must have leader pins and bushings or some similar guidance system.

CLASS II UNIT INSERT

1. Detailed mold design recommended.
2. Insert retainer to be uniform hardness of at least 165 BHN.
3. Cavities and cores must be 280 BHN or higher.
4. Water channels to be included.
5. All other extras are optional.

CLASS III UNIT INSERT

Can be constructed from aluminum, cast metal, cast epoxy or any material with sufficient strength
to produce minimum prototype parts.

Important: Refer to the general specifications to complete the details of this section, except for prototype molds.