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lInvestment casting is popular in the manufacture of precision metal parts, but there are also inevitable quality issues throughout the production process. Therefore, in order to ensure the quality of products, investment casting quality control must be done before delivery.

we offer a wide range of in-house investment casting quality verification and product testing services such as NDT, designed to provide our customers with the highest quality cast products. No matter where the product is used, every precision investment casting is inspected and approved before leaving the factory.

eye exam

Based on investment casting industry standards and customer specific requirements, visual inspection is required to ensure good casting quality from start to finish. Visual inspection must be carried out 100% and needs to ensure that the surface of the investment casting is free of defects. Common surface defects of investment castings are: oxide scale, pores, blisters, cracks, shrinkage holes, etc. Any castings with such defects must be picked out and cannot be delivered to our customers. And all inspection results must be recorded and stored for all products produced by our foundry.

Dimensional inspection

We all know that investment casting is a custom casting process for various components. And different products have different dimensional and tolerance requirements. The investment casting process can help you obtain precision products with ideal dimensions and dimensions for high precision. Even if some tolerances cannot be obtained directly by casting, we can achieve the result by further machining. However, while finished products sometimes look perfect, that doesn't mean they can be put to work without question. In this case, dimensional inspection is essential for assurance. The following are commonly used dimensional inspection methods in our foundry:

Dimensional Inspection of Investment Casting

1) Measuring Tools - This is the most direct and easiest way to manually test dimensions and tolerances. In order to ensure that the products are qualified, we need to test the products one by one according to the drawings and measuring tools. Commonly used measuring tools for investment castings include: vernier calipers, depth indicators, dial indicators, etc.

2) Test Gauge - Made to dimensions that may affect product assembly or use. For threaded holes, we can buy go and non-go gauges directly from the market according to thread specifications. Detecting gauges are mostly used in situations where it is not possible to measure dimensions directly.

3) CMM - is the most accurate way to test product size. But this adds to the manufacturer's cost, as CMM equipment is expensive and only a few foundries have such instruments.

chemical composition test

Investment casting parts are formed by pouring molten metal into a runner. This makes it possible to cast products from a wide variety of metal alloys, with different materials having their own characteristics. The wrong composition of any element can cause a lot of trouble for our clients. So we need to test the chemical composition of the material accordingly. Material testing is performed by a spectrometer. Our quality control procedures for materials are: When ordering raw materials from the material factory, request and provide a material certificate. And before production, we compare the composition of each element through a spectrometer, and the recorded results show whether the material is within that range. And after casting or heat treatment, our test instruments will help us to confirm whether the material composition changes during the production process. And record each batch of test results in our laboratory for future traceability.

To confirm the performance of investment castings, mechanical tests are performed to confirm product quality. Testing confirms performance to specified mechanical requirements. The following mechanical property tests can be performed to confirm proper casting quality.

Hardness Testing - Tested when there is a hardness requirement for investment castings. Hardness test results are mostly expressed in HB or HRC.

Tensile Testing - A destructive testing process that provides the ultimate tensile strength, yield strength, elongation, and reduced area of ​​a product.

NDT

Dye Penetrant Testing - One of the Nondestructive Testing Methods for Investment Castings

NDT (Non-Destructive Testing) allows us to test the quality of investment cast parts without causing any damage. The most common methods are listed below:

Dye Penetrant Testing: Surface defects such as tiny cracks, pores, or other surface defects are sometimes difficult to detect with the naked eye. DPI is an inspection method for surface defects in all alloy investment castings. During this inspection, a colored dye solution is applied to the surface of the casting. Dyes suspended in penetrating oil can enter surface defects. When a special developer is used, the defects show up clearly under a special "blue" light. The solution is to detect any cracks or other surface defects due to pores or gases generated on the surface.

Magnetic particle inspection: A non-destructive testing method for finding defects through the accumulation of magnetic particles at the location of the defect. MPI testing is convenient and affordable. It detects small cracks on or near the surface of investment castings. Cracks and defects have different magnetic properties than surrounding material. Their presence interrupts the magnetic field, causing deformations that indicate the shape and location of cracks or voids.

X-ray inspection: This non-destructive method is used to inspect investment castings for internal defects such as shrinkage cavities and inclusions.

Ultrasonic Inspection: Evaluate and diagnose various defects such as cracks, inclusions, pinholes, etc. Defects in ultrasonic waves can be detected by their effect on the propagation of ultrasonic waves based on the acoustic properties exhibited. due to material defects.