Investment castings offer the best solution to achieving near to shape parts, with a high degree of dimensional accuracy and good surface finish, says the Dean Group International. And for less aesthetically demanding applications, commercial grade investment casting is a cost-effective alternative to sand casting.

At the quality end of the market, Dean Group has recently been producing castings in stainless steel that are mirror polished. The appearance is almost identical to chrome plating but the benefit is that the parts can be easily reworked if damaged. The process also allows more complicated designs than the traditional die cast and plated route. The company says this is ideal for taps, bathroom fittings and beer fonts.

And where the requirement for these high standards are not imperative the company can also offer commercial grade investment casting. This process offers all the benefits of premium grade investment casting; no need for draft angles, good dimensional accuracy and surface finish, and good integrity but at a fraction of the cost. This process is ideal for applications that are less aesthetically demanding, commercial vehicles, clamps and brackets and so on, giving significant benefits over the previous default option of sand casting.

Getting the investment casting process right is the key, and simulation software makes this simpler to achieve.

“The investment casting process is technically involved and each manufacturing process stage needs to be controlled closely to achieve the benefits and to maintain the quality”, says Michael Fielding, Dean Group’s Business Development Manager.

A key part of the initial design stage involves the use of bespoke casting simulation software, in conjunction with Solidworks 3D CAD design software. The simulation software numerically analyses the way in which the molten metal solidifies in the investment casting shell.

“Getting a good simulation result can be time consuming and may require a number of runs to achieve the optimum results; but this time is crucial, as once a good result is achieved, the resultant component will be free from shrinkage defects and porosity; and it will stay this way! If you fail to get it right, it will stay wrong, for ever and a day!” says Mr Fielding.

“In achieving the optimised design for the investment casting it may be necessary to change a number of things from the feed, or ingate positions, their size and shape and number of, to the orientation of the casting, or even changes to the design of the part itself. The Dean Group has used this simulation software now for many years. It is fundamental to the success and control of our manufacture and all parts, whether produced in Manchester or by our supply partners in China, go through the same procedure.”

The Dean Group serves industries as diverse as rail, commercial vehicles, architectural fittings, oils & gas, defence and beer dispensing.

http://www.engineeringcapacity.com/archive101/2009/january