What is standard tolerance for aluminum die casting products?

As we know, Aluminum die casting technique enables a higher manufacturing rate than many other aluminum alloys, which also tends to be economic.  It yields light weight but durable parts ready for any application.

To designer, the dimensional tolerance will be very critical. If you are very familiar with the dimension tolerance, you can better control the feasibility of the production, so that you may save much money on the design. If the tolerance is ignored during design, there may comes much machining in production which will make the cost higher. We will introduce some tolerance as below which may be mostly used.  

• NADCA dimensional tolerances:

  
  

NADCA provides a set of cast component tolerance standards regarding dimensions over the parting line. These measurements are determined by the projected area of the die casting and expressed in inches squared.

• Beow table is the standard tolerances for aluminum alloys:

• Below table is the precision tolerances for aluminum alloys:

• Below table is the ISO 2768 dimensional tolerances:

• Below is table for CT 10dimensional tolerances:

• Linear Dimensions: Standard Tolerances

Because dies wear over the course of producing castings, it should be noted that the number of shots on a die prior to repair or replacement will be less for tighter die casting tolerances and greater for wider casting tolerances.

• What is Parting Line: Standard Tolerances?

• Parting Line Tolerance is the maximum amount of die separation allowed for the end product to meet specified requirements of form, fit and function. This is not to be confused with Parting Line Shift Tolerance which is the maximum amount die halves shift from side to side in relation to one another.

• Parting Line Tolerance is a function of the surface area of the die from which material can flow from one die half to the other. This is also known as Projected Area.

• Projected Area is always a plus tolerance since a completely closed die has 0 separation. Excess material and pressure will force the die to open along the parting line plane creating an oversize condition. The excess material will cause the part to be thicker than the ideal specification and that is why Projected Area only has plus tolerance. It is important to understand that Projected Area Tolerance does not provide Parting Line Tolerance by itself. Part thickness or depth must be factored in to give a true idea of Parting Line Tolerance. Parting Line Tolerance is a function of part thickness perpendicular to the Projected Area plus the Projected Area Tolerance.

• Engineering & Design: Additional Specification Guidelines:

• What is Acceptable Ejector Pin Marks?

Ejector pin marks on most die castings may be raised or depressed .015” (.381 mm). Raised ejector pin marks are preferred for optimum production. Larger castings may require additional ejector pin tolerances for proper casting ejection.

• What is Ejector Pin Flash?

Ejector pin marks are surrounded by a flash of metal. Normally, ejector pin flash will not be removed, unless it is objectionable to the end use of the part. Alternatively, ejector pin flash may be specified as crushed or flattened. In the case of either nonremoval or crushing/flattening, flash may flake off in use. Complete removal of ejector pin marks and flash by machining or hand scraping operations should be specified only when requirements justify the added expense. With each die casting cycle, the die opens and the ejector plate in the ejector half of the die (Fig. A) automatically moves all ejector pins forward (Fig. B), releasing the casting from the die. Then, the die casting is removed from the die manually or mechanically.

• General Guidelines for As Cast Surface Finish on Aluminum Die Casting Parts:

The specification of external surface finish requirements is desirable for selected aluminum die casting applications and in the case of some decorative parts, essential. The purpose of the guidelines presented here is to classify as cast surface finish for die castings into a series of grades so that the type of as cast finish required may be addressed and defined in advance of die design. 

These guidelines should be used for general type classification only, with final surface finish quality requirements specifically agreed upon between the die caster and the customer.

• What materials can be die cast?

Most of die casting products are made from non-ferrous metals, specifically in zinc, copper, aluminum, magnesium, lead, pewter, and tin-based alloys. It depends on the types of metal being casting, a hot or cold chamber machine can be used.

Our Quality Policy and ISO 9001 certification ensures good quality and service.  Whether you’re in the medical, automotive or lighting industry, you can find a solution to your die casting needs at Shunho Precision. Please Contact us today with the die casting projects you have in mind, and we’ll work with you to create an amazing products for your business.