Business News: Additive & Conventional Manufacturing – Hybrid Manufacturing Techniques From Croft Filters

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Written By: Mark Armstrong

The following is a news story from Croft Filters …

Croft Filters, based in Warrington, England, have been supplying custom filtration and separation solutions for over 31 years. Over this time, Croft has developed a reputation for their quality, bespoke service through manufacturing a variety of products for specific requirements. These products have included Filtration Cones, Baskets & Screens, Disc Filters and Filtration Housings amongst others, and they are made with Wire Mesh, Wedge Wire and Perforated Plate, depending on the product’s design. Croft continues to supply a wide range of industries including Oil, Gas, Pharmaceutical Food and Beverage. As a result of this and due to the application requirements, most of Croft’s products are manufactured using Stainless Steel 316L.

Croft continues to meet customer’s demands by heavily investing into research and development of their custom filtration solutions. In 2013, Croft invested into Additive Manufacturing, specifically Selective Laser Melting (SLM), in order to develop new innovative filtration solutions.

Additive Manufacturing (AM), also known as metal 3D printing, is the process of creating a three-dimensional component in a series of layers. The process uses a metal powder, and in Croft’s case this is Stainless Steel 316L. The powder is spread evenly across a build plate; a laser then melts the powder according to a CAD file. The build plate then drops 50 microns and another powder layer is added. The laser then melts this layer to the previous layer. The process is repeated until the final part is complete. This process differs to subtractive methods, only using the required material to build the part as any excess powder that has not been fused is recycled back into the machine’s powder delivery system.

Benefits of the Additive process include part-weight reduction, multi-part to single component and expanded design capabilities, and they allow Croft’s customers to re-think their approach to their designs in order to improve the efficiency, utility or aesthetics of their parts.

Customer Focused Product Development

Over the past 15 years, Croft Filters has been supplying their customers with small cone filters. Manufactured from Stainless Steel 316L mesh with a punched flange spot welded onto the mesh, these conventional filters are used within machinery processes.

Although it’s a simple design, manufacturing these filters can be tricky. The mesh is first cut to shape and welded using a seam welder. Getting the mesh to a point can be challenging, as the weld seam must run completely down the filter so that there are no gaps in the mesh. Due to its design, the weld seam also covers up the mesh’s open area therefore blocking each cone slightly.

To overcome these manufacturing issues and to improve the filters open area, Croft decided to trial Additive Manufacturing, specifically Selective Laster Melting, to produce an AM cone Filter that did not have to be assembles and maintained the desired open area.

After developing a number of different prototypes, Croft successfully manufactured AM Cone Filters that had the desired strength and open area. These cones did not have any weld seams, so the open area was not obstructed. However, there was one issue with the Additive Filters, specifically their flanges.

Due to its flat surface and build orientation within the Additive Manufacturing build chamber, the flange on the filter collects a lot of heat when being built. This heat causes the powder layer to blister; this results in a poor surface finish and can also distort the filter’s dimensions.

To overcome this issue, Croft trailed different AM manufacturing techniques, from changing the build parameters to changing how the part was orientated on the build plate; however, no attempts were successful.

Hybrid Manufacturing

Failing to overcome the issue of the flange blistering, Croft decided that conventional manufacturing techniques would be better to produce the flanges of the Cone Filters. This resulted in the development of a new AM and Conventional hybrid that utilised the advantages of the Additive mesh alongside the reliability of a conventional flange.

To manufacture the Hybrid AM Filters, the mesh is first printed as usual. However, the mesh now has a solid ring at the base of the cones rather than a flange. This ring then allows the conventionally-punched and formed flange to be laser-welded onto the AM mesh.

The Hybrid filters have been a success. The customer was pleased that Croft managed to improve on their product’s design so that the filters would perform more effectively within the Customer’s machinery.

Croft continues to invest heavily in product innovation through research and development. This includes working with universities and other Additive Manufacturing professionals in order to deliver advanced AM products. This is strengthened further by Croft’s 31 years using conventional manufacturing techniques.

Quality of both product and service has been the key to Croft’s success; the company takes great pride in understanding their customer’s needs, quickly supplying them with a high-quality product that exceeds Customer’s expectations.

For more information about Croft’s Custom AM solutions, you can visit www.filters.co.uk.