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A European medical-device company approached Unicut Precision three years ago to make components for a device to provide needleless administration of insulin to diabetes patients.

Unicut consequently won the contract, but today most of the components being produced as part of the initial GBP230,000 contract – involving 10,000 sets of 14 parts – bear no resemblance to the original quotation drawings.

Jason Nicholson, joint managing director of Unicut, said: ‘Over the past two-and-a-half years we have worked closely with this Dutch customer, giving design-for-manufacture advice to help develop the components.

‘In addition to general production engineering input, some parts were redesigned as two separate items to simplify production.

‘However, due to the capability of our Citizen sliding head and Miyano fixed-head turn-mill centres, others were combined into more complicated single parts in order to ensure geometric relationships of features, simplify the final assembly and reduce production costs, as well as guarantee function of the critical needleless device.’ As part of its customer-support service, Unicut directors also provided specification advice on material, changes to material specifications for machinability, as well as protective coatings to prevent wear on critical components and ensure long-term accuracy of the device and to improve performance.

During this initial period, the flexibility of Unicut’s 25 mill-turn centres and non-contact automatic measuring systems enabled the companies to work closely together on prototype development.

This process manufactured samples to maximum, mid and minimum tolerances, so that product development trials could be performed to ensure that functionality of the assembled device would never be compromised.

Unicut has worked for several years with the medical sector and after almost 12 months into the Dutch project it was approached by a UK company to work on the development of an electronic-assisted device to perform dial-up dosage and needleless injection of other types of drugs.

Charles Kenny, Unicut’s joint managing director, said: ‘This was a completely different ball game, requiring even stricter quality systems and additional levels of traceability.

‘While the Dutch product involved 14 parts, the UK customer’s device (which is now under contract as well) comprises 12 with an initial production of 20,000 sets predicted to rise to 50,000 units/year.’ Needleless drug administration devices deliver, in a fraction of a second, a precise micro-thin stream of insulin through a specially designed precision orifice at high velocity that penetrates the skin and is deposited into the subcutaneous (fatty) tissue.

They eliminate risk of accidents from needle-stick injuries and contamination, are ideal for people that dislike injecting with needles or that can develop skin problems, and remove any disposal problems associated with sharp objects.

Key to the success of the prototyping and pre-production work was Unicut’s ability to take total responsibility on both projects for outsourced processes such as specialist deburring, heat treatment, wire EDM, plating and surface finishing, allowing parts to be delivered directly to the customer ready for assembly.

As the projects moved towards pre-production, both Unicut directors reviewed their production and quality procedures to create a seamless transition.

As part of the investment, two additional machine setters and two Citizen K16 CNC sliding head lathes were installed to free up production on the higher specification Citizen M32 machines and a Miyano BNJ-42 fixed-head turning centre.

A programmable Durr component wash was upgraded to the latest specification and a cleanroom was built.

The components range from 1.5mm diameter by 15mm long in 316 stainless steel to 26mm diameter by 110mm long, and the tightest tolerance is within +0.005mm.

One particular collet-style component in titanium has slots 0.2mm wide by 9mm deep, which have to be subcontracted to a tooling company to be produced using wire EDM.

Parts are made from a variety of materials such as stainless steel, S1 tool steel, titanium, aluminium and plastics.

The single-cycle floor-to-floor times vary from between 45 seconds and five minutes, with each component being deburred automatically as part of the machining operation.

A number of components have to be sent out for specialist operations such as heat treatment, bead and vapour blasting, nickel and hard anodising, laser etching, thermal deburring and silk screen printing – all under Unicut’s control and responsibility.

As part of the process development, Unicut tailored the machining processes to accommodate the required finish tolerances, especially to allow for the hard anodised plating.

This meant various thicknesses of coating layers had to be accommodated with special process tolerances on features such as grooves, recesses and bores as well as diameters, threads and four critical conical tapers on cross-holes that break into the main bore of the body component.

Unicut was able to eliminate any grinding and other finishing processes, incorporating these into the turn-milling cycles, which has reduced lead times and costs.

As an example of specific drawing requirements, within the machining cycle on one component Unicut has to guarantee within 0.5 degrees the position of the start of a thread pitch line relative to slots milled at the other end of the 80mm part, to allow the precise medical dosage to be quickly and accurately set by the user.

A highly accurate cam profile on one component is also milled on the Citizen M32 to ‘fire’ the drug through the pores of the user’s skin.

Quality control and systems within Unicut were critical in both projects.

Kenny said: ‘We had to comply with one customer’s install qualification (IQ), operational qualification (OQ) and part qualification (PQ) standards.’ For this, Unicut had to control the production process and apply full traceability from material order to component despatch using its Datatrack production control and scheduling management system (with minor modification), which provided the up-to-date information the customer sought.

To satisfy the IQ requirement, Unicut had to furnish details on the type of machinery and equipment being used, its history and service records, procedures for programming, tooling and inspection and provide documentation covering record keeping, including usage, resetting and tooling records, capability studies, details of the personnel involved, health and safety compliance, and environmental and risk assessment.

PQ covered set down procedures, works order and stock control, production records (especially on outsourced processes) inspection routines, gauge control and reporting procedures.

The initial five components had to be 100 per cent inspected for every drawing detail and any production improvements and changes of process had to be documented.

Regular process capability studies were listed under PQ procedures with reporting and actions taken that enabled track-back and situation recovery disciplines to be initiated should any parts be found not to comply.

Nicholson said: ‘Our extensive use of non-contact, video-based measurement with its automated reporting has proven very beneficial to the inspection and recording of the majority of component feature dimensions.

‘It also enabled almost immediate electronic feedback to be provided to the customer for discussions over quality and design issues, providing detail and visual measurement analysis and fully automated SPC data capture with tabulation at the touch of a button.

‘This saved us hours of almost endless checking and eliminated any bias and subjective debate.

‘It also helped to quickly build confidence with the customer over the levels of consistency we could maintain over a batch of parts.’

Unicut Precision

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