Processing Die Cast
Obtaining a casting design is the first stage in the journey of an end-use product, followed by the selection of surface finishes. Many customers find it challenging to choose and match an appropriate finish for their final product. As it is not always an easy step, we have decided to provide you with a run-through of factors and properties which should be considered when selecting from a variety of surface finish options.
First, it is worth making sure that you need a surface finish at all. It may surprise you but not all castings need it.
Recent improvements in alloys have enabled producing raw but stunning quality castings, which would previously require an additional surface finish. For instance, traditionally to achieve corrosion resistance of castings made of alloys ENAC 46000, ADC12 and A383, it was necessary to use additional surface protection. The breakthrough came with new advanced alloys which, in many cases, make additional finishes redundant.
When is a surface finish not required?
Each alloy type has its own characteristics. Alloys vary in terms of their resistance to corrosion, elongation, electrical conductivity, and other properties. Once you have chosen an appropriate alloy that matches the mechanical and physical properties of your product, an additional surface finish additional protection may no longer be required. Moreover, if the product is intended for technical use only, and its decorative appearance is of lesser importance, you might be satisfied with a raw cast, which would also significantly decrease the manufacturing cost of your end-use product.
When will you need to use an additional surface finish?
A surface finish may be applied in order to obtain shining, matt, satin, colourful and polished effects. Additional post-processing can also help to increase the product’s resistance to atmospheric corrosion and mechanical properties.
If you are looking for a different surface finish than the ones described below, or are unsure about which surface finish would best match your product, contact our experienced engineers, who will assist you with your decision.
Vibratory finishing
The vibratory tumbling finishing process also called trovalization involves vibrating metal parts with ceramic, plastic or metallic media, with the addition of booster fluids and water.
Depending on the chosen medium, material granules and manufacturing process, this technology is ideal for mass production of small and medium size items and is used for deburring, polishing, and softening the sharp edges of manufactured components.
Shot blasting
Shot blasting is a process of surface finishing during which fine abrasive material in the form of metallic, mineral or glass beads is accelerated towards the workpiece at high speed.
Shot blasting and peening may be used in the surface finishing of lightweight products of just a few grams to heavy weight casts of even several dozen kilograms.
This process is used to increase the strength of a component, remove or soften its sharp edges, clean its surface or prepare it for the application of an additional layer.
Polishing
The process of die cast polishing begins with the preparation of the surface of an item on belt grinders and subsequently on customised polishing wheels.
Depending on the type and quantity of the manufactured product, polishing can be performed manually or it can be automated.
Cataphoresis
Cataphoresis, i.e., electrophoretic painting, in practice means immersing an item in a bath of water-based paint solution, which is connected to electricity by means of electrodes.
Proper preparation of the item’s surface before electrophoretic painting guarantees high anti-corrosion resistance of up to 1000h in a salt spray chamber as well as protection against environmental exposure.
In terms of its appearance, the coating is smooth in black with high aesthetics.
Powder Coating
Powder coating is an effective technology for painting the product’s surface with powdered paint using the electrostatic spray method. It is often used as a decorative or anti-corrosive surface finish.
To ensure adequate adhesion of paint and anti-corrosion protection, the product surface should be properly prepared beforehand by shot blasting, degreasing and surface passivation.
Painting is possible in any RAL colour with a different degree of gloss, matt and paint structure.
Heat Treatment of castings
Heat treatment of pressure die casts is used in the case of products, for which it is important to eliminate the stresses that have resulted from metal solidification or its processing. In addition, it is intended to make the internal structure of the casting more uniform and to maintain the casting’s dimensions.
Heat treatment significantly increases the strength of the casting and improves its anti-corrosion resistance.
Anodizing
Anodizing is an electrochemical process applied to the surface of a product, which occurs in several stages. For the product to be anodised, it has to be properly cleaned and degreased.
This coating can serve both decorative and technical purposes. It is available in a variety of colours and is known to enhance the product’s surface strength as well as its resistance to corrosion.
For aluminium die casts, technical anodizing is mainly used in order to increase the product’s anti-corrosion capabilities and abrasion resistance.
Galvanising
Galvanising is the process of producing thin, permanently adhering coating on various materials.
It is used to obtain decorative surface finishes and to increase resistance to abrasion, corrosion, and erosion.
Galvanising of products can be carried out in a variety of coating options, including chrome, satin chrome, tin, copper, brass, nickel, black nickel, gold silver plating and zinc plating.