Class 101 Mold
Cycles: One million or more
Description: Built for extremely high production. This is the highest priced mold and is made with only the highest quality materials.
Detailed mold design required.
Mold base to be minimum hardness of 28 R/C.
Molding surfaces (cavities and cores) must be hardened to a minimum of 48 R/C range. All other details, such as
sub-inserts, slides, heel blocks, gibs, wedge blocks, lifters, etc. should also be of hardened tool steels.
Ejection should be guided.
Slides must have wear plates.
Temperature control provisions to be in cavities, cores and slide cores wherever possible.
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.
Parting line locks are required on all molds.
Class 102 Mold
Cycles: Not exceeding one million
Description: Medium to high production mold, good for abrasive materials and/or parts requiring close tolerances. This is a high quality, fairly high priced mold.
Detailed mold design required.
Mold base to be minimum hardness of 28 R/C.
Molding surfaces should be hardened to a 48 R/C range. All other functional details should be made and heat
treated.
Temperature control provisions to be directly in the cavities, cores, and slide cores wherever possible.
Parting line locks are recommended for all molds.
The following items may or may not be required depending on the ultimate production quantities anticipated. It is
recommended that those items desired be made a firm requirement for quoting purposes:
Guided Ejection
Slide Wear Plates
Corrosive Resistant Temperature Control Channels
Plated Cavities
Class 103 Mold
*Cycles: Under 500,000
Description: Medium production mold. This is a very popular mold for low to medium production needs. Most
common price range.
Detailed mold design recommended.
Mold base must be minimum hardness of 8 R/C.
Cavity and cores must be 28 R/C or higher.
All other extras are optional.
Class 104 Mold
*Cycles: Under 100,000
Description: Low production mold. Used only for limited production preferably with non-abrasive materials. Low to moderate price range.
Mold design recommended.
Mold base can be of mild steel or aluminum.
Cavities can be of aluminum, mild steel or any other agreed upon metal.
Class 105 Mold
Cycles: Not exceeding 500
Description: Prototype only. This mold will be constructed in the least expensive manner possible to produce a very limited quantity of prototype parts.
May be constructed from cast metal or epoxy or any other material offering sufficient strength to produce
minimum prototype pieces.
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The Society of the Plastics Industry, or SPI, establishes standards for the United States plastics industry.
Among the SPI standards is one defining the degree of polish on the inner surfaces of the molds used to form
plastic products.
The SPI standards specify 12 grades of mold finish ranging from mirror-perfect to dull. Various companies offer
illustrative sample kits consisting of steel discs or strips polished to the different SPI grades.
Shiny Finishes
SPI grades A-1, A-2 and A-3 specify high gloss finishes on hardened tool steel molds buffed to a mirror sheen with fine diamond powder suspended in oil. Plastic parts made to these grades show no mold parting marks or tool or machining marks. An A-1 mold finish has no more than 1 millionth of an inch deviation from perfect. An A-2 finish allows up to 2 millionths of an inch deviation, while an A-3 finish allows deviation of up to 3 millionths of an inch from perfect. These super smooth and shiny finishes are very expensive and time-consuming to achieve. They are specified to make plastic mirrors, visors and other optical plastic goods.
Semi-Gloss Finishes
SPI grades B-1, B-2 and B-3 specify semi-gloss finishes with some sheen, on hardened tool steel molds polished with ultra-fine-grit sandpaper or emery cloth. Again, plastic parts from these molds can't show mold, tool or machining marks. Grade B-1 allows a 3 millionths of an inch deviation from perfect. Grade B-2 allows up to 5 millionths of an inch deviation, while Grade B-3 allows up to 10 millionths of an inch deviation from perfect.
