Simplified process with Firstcut and Protomold

For the past 43 years, Knaresborough-based BNL (UK) Ltd has specialised in the design and manufacture of plastic bearings. These offer many advantages over traditional steel bearings, such as easy feature integration, whole-system cost reduction, corrosion and chemical resistance, reduced weight and reduced friction, as well as exceptionally low wear rates and low maintenance requirements.

No wonder then, that the company is experiencing high levels of demand for its products and services. Recently, a large, global company specialising in security systems approached BNL, with a brief to design a new version of dome-type CCTV camera - similar to the ones typically installed at facilities such as casinos, banks and retail stores.

BNL Project Engineer Ewan Burnett explains: "Around two years ago we were approached by a big player in the CCTV market who wanted us to come up with the next generation of an established camera design. The design had been successful for the previous 15 years, but was due for an update. Our customer wanted something new, with an improved, internal PTZ (pan-tilt-zoom) mechanism."

Mr Burnett and his team set about a collaborative design process in conjunction with the customer's engineering department. However, although the facility at Knaresborough has many injection moulding machines and a fully equipped prototyping department, the decision was taken to outsource the initial stages of the project.

Mr Burnett says: "We were close to capacity at Knaresborough so it made good business sense to find an external supplier. We found Proto Labs via an internet search and decided to evaluate their facility at Telford, discovering that their speed of response was very impressive."

After uploading the 3D CAD model into the FirstQuote automated quotation system, initial prototypes of the parts required for the new PTZ mechanism were machined from acetal using the Proto Labs Firstcut service. Firstcut is a subtractive rapid prototyping process that delivers CNC machined parts in materials with suitable mechanical properties.

Simple to use

Mr Burnett syas: "FirstQuote could not have been any simpler to use. We uploaded the CAD model and within hours we received an online quote in which we could change parameters such as quantity, delivery, material and finish, and the price would be instantly updated. Our experience was similar using ProtoQuote for moulded prototypes. The parameters are slightly different but it's just as straightforward."

Following testing of the machined prototypes and a small number of design changes, the next stage was to produce moulded prototypes. A downside to moulded bearings is the potentially lengthy lead-time demanded by the ultra-precise hard tooling.

Mr Burnett says: "As a consequence we decided to take the aluminium tool route as this would still allow us to perform full, functional testing on actual moulded parts. Furthermore, because of the speed of the Protomold service we would also be able to develop hard tools in parallel. Any issues arising from testing could quickly be fed into the hard tooling process. This concurrent engineering strategy was invaluable in expediting a final solution for our customer."

The PTZ mechanism comprises three sub-assemblies with 15 moulded parts in total, made from a material specified by BNL All of the prototype parts (except the bearing tracks which are IP protected) were produced on Protomold tools - the biggest of which was the pan base with a diameter of around 150mm. In total, two runs of around 200-off (of each part) have been completed using Protomold tools, with some minor design modifications to the parts applied between each run.

Mr Burnett says: "Some people think aluminium tools are only useful for a handful of parts but nothing could be further from the truth. Proto Labs has the view that their aluminium tools are for life, and that if wear starts to become evident, they will undertake maintenance to rectify."

BNL is now continuing production runs using its in-house-developed hard tooling, following the launch the new CCTV camera in August 2013.

Mr Burnett concludes: "We have found Proto Labs to be extremely responsive, and since the start of this project in 2011 we've developed an amazing relationship together. In fact, in 2012/2013 we entered dozens of different parts into the ProtoQuote automated quotation system - these are now at various stages of development. Furthermore, our entire design team are also now exploring the benefits of using Proto Labs. Overall, the advantages offered by Firstcut and Protomold have effectively changed the business model at BNL.

To learn more about Proto Labs please visit their website at www.protolabs.co.uk, and follow the links for further information about Protomold and Firstcut.