Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel halves which have been machined into shape. Most die castings are made from non-ferrous metals, specifically aluminum, zinc, copper, magnesium, lead, pewter and tin based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.

The die casting machines at Sigma are mainly of Toshiba-Japan and Zitai-Taiwan make. There are over 45 cold chamber machines with capacities ranging from 150 tons to 900 tons - capable of producing parts ranging from 0.03 Kg to 8.8 Kg, subject to projected area limitations.

Sigma handles a wide range of aluminum alloys to meet customers’ requirements.

The hot chamber machines at Sigma are mainly of Producer, Taiwan and LK, China makes. There are over 35 machines with capacities ranging from 12 tons to 250 tons - capable of producing parts ranging from 0.04 Kg to 2.50 Kg subject to projected area limitations.

Sigma handles a variety of alloys to meet customers’ requirements.

Also known as permanent mould casting gets their name from the fact that the process utilizes permanent metal moulds instead of temporary sand moulds for the casting process. Cast iron is the most commonly used mould materials as it offers great reliability during casting. The cores are made from other metals or sand. The cavity surface of the mould is coated with fine layers of material that have good heat-resistant properties such as clay or sodium silicate. The moulds used in casting are pre-heated up to 200°C. before the molten metal is poured into the cast cavity. Proper thermal balance is to be maintained throughout the casting process. This is done through a variety of ways including external cooling techniques using water or relevant radiation techniques.

Permanent mould casting has the advantage of offering relatively lower design and development costs as well as productions costs.

At Sigma, the Al-br parts are manufactured for high and medium voltage fuse cut-outs through permanent mould gravity die-casting process.

Raw material is tested on the spectrometer to determine its chemical composition. Manufacturing process starts with melting followed by feeding the molten metal into the casting machine. Raw cast parts go down stream process like trimming, machining and surface coating.

Green sand casting is a low cost means of producing many of the engineered components of today's modern equipment and machinery. The term "green sand" is known principally because of the moisture content within the sand and it is a prepared mixture of silica sand (both new and reclaimed), various bonding clays, carbonaceous materials and water. To get mould, the prepared sand compacted around the pattern to take shape of the desired casting. The sand mold is vibrated until it is released from the casting after solidification.

These castings can vary greatly in size and weight, ranging from a couple grams to several kilograms. In general, the sand casting process involves the use of a melting furnace, liquid metal, pattern and sand mold where molten metal poured under gravity into sand moulds. The patterns are designed and made in in-house tool room. Sigma is capable to produce sand castings out of Cu, Zn, Al alloys and cast iron.

Sigma has “Sinto” Japan make automated high pressure molding lines. The high pressure molding lines are capable to produce 120-180 molds / hr and capable to cast parts up to 20 kg. Sigma is equipped with Induction furnaces, CNC and VMC machines, heat treatment capacity, plating and powder coating facilities.

Sigma has state-of-the art powder coating facility equipped with automated pre-treatment line and has the ability to use a wide range of colors. The facility is environment friendly which avoids volatile organic compounds (VOCs), thus ensuring corrosion resistance and maintains consistent film thickness of 40-90 µ.

Sigma’s powder coated products attain good mechanical properties and pass demanding impact, abrasion resistance and hardness tests complying with the UL standards.

Sigma’s state-of-the-art in-house paint testing lab is equipped with Spectrophotometer, Tri-Gloss master gloss meter and D65 chamber. The liquid painted components attain good mechanical and chemical properties and pass the demanding impact, abrasion resistance and hardness tests complying with the UL standards.