Die casting standard

  1. Positive Metal – Due to the nature of the investment aluminum casting process, random positives are encountered and these vary by alloy and part configuration. Unless otherwise agreed, these will be limited to a size of 0.015-0.030″ high by 0.125″ by 0.125″ and no more than one per 1″ square. Smaller defects of all sizes may be present at random but not in places where they interfere with the function of the part – such as holes, knurls, or lettering. Positive metal requirements other than this will be specified by the customer at time of quotation.
  2. Surface Pits – Random negatives may also occur. These will be limited to 0.030-0.060″ by 0.030″ deep in size, no more than one of those per 1″ square. Unless otherwise specified by the customer, smaller negatives may be present, providing they do not interfere with the function of the part.
  3. Nonfill – Edges may be rounded up to 0.015″ radius even though tooled sharp. Sharper or more rounded edges can be provided as agreed between purchaser and foundry.
  4.  Cleanliness РAluminum die Castings will be sand, grit or shot blasted to remove casting and heat treatment scale or other foreign material. Stainless steel castings will not be pickeled or passivated unless specified. Castings will be provided with sand blasted, grit blasted or vibropolished surfaces and be of uniform appearance typical of those processes. Unless the purchaser specifies a rust preventive treatment, some light rusting may be present.
  5.  Linear Indications РParts will contain no linear cold shuts, visual cracks, or visual shrinkage, except as agreed with customer.
  6.  Surface Texture РThe surface texture standards for investment casting will be 125 RMS maximum.

The foundry will establish a casting method that is capable of producing castings that show less than 10% shrinkage porosity in any cross section area. Shrinkage will not be present in an area where subsequent machining will reveal it as a visual surface defect.
Internal Defects
Some limited quantity of internal defects, including gas holes, slag entrapment, non-metallic inclusions, or porosity may be encountered by the purchaser. If these render the casting unusable, methods of inspection and acceptance limits to exclude such defects will be established by the purchaser and the foundry prior to further production of the die casting.
This is not, or intended to be an all-inclusive specification, but is meant more as a guideline. Any quality conditions or inspection criteria not addressed here or that are beyond the tolerances or specifications listed here can be negotiated in the purchase agreement.