Case study

Challenge

• The customer was looking to re-design a very compact benchtop medical diagnosis machine.
• New business model to loan the instrument to GP surgery’s, and charge solely for the tests made. This would enable far greater access to lifesaving DNA testing.
• Instrument manufacturing costs had to be cut by ⅔ to support the new commercial strategy. This meant that the previously used Swiss and German mechanisms had to be replaced as part of a major cost-down exercise.
• The machine still had to perform reliably, with very high accuracy, and a challenging longevity target was set for the main laser positioning mechanism.
• Although not FDA certified, the machine had to be built to Class III standards, which required detailed testing, validation, and manufacturing processes throughout.

Solution

• Our application and product design teams spent considerable effort with the customer, to fully understand what performance compromises could be accepted, to achieve the significant cost-down.
• The customer understood the scale of the challenge and offered enough time for us to prototype, design, test and validate several solutions.
• The final accepted design used a 1000:1 gearbox 12mm gear motor with very high resolution encoder and a slider cam. This enabled us to hit a repeatable positional accuracy of 8μm.
• We devised a driving algoritm to reliably home the slider, and soak-up inherent backlash.
• The mechanism experienced low loads, but frequent actuation. We built a custom longevity testing machine to prove that our motor sub-component optimisations were sufficiently robust.

Results

• Our mechanism hit 90% of the prior mechanisms in-application performance at ⅓ cost!
• The customer was initially skeptical that we could achieve this result, but we were confident that the previously used Swiss and German mechanisms were simply over-engineered for this application.
• The customer was delighted and we were very proud of the result.
• Our testing infrastructure was critical in proving that our mechanism was reliable and robust enough.
• Our manufacturing infrastructure was audited extensively, passing first time, and all mechanisms were serialised and extensively tested prior to shipping.
• Affordable DNA diagnosis testing will soon be coming to a healthcare provider near you!

STAGE 1

Designing for application

• We were tasked with designing a high-precision mechanism to position a laser within a piece of medical analysis equipment.
• Our application-specific mechanism solution, capable of 8 micron accuracy, was based around a miniature 12mm gear motor, high accuracy encoders and a precise cam-based linear slide.
• Our Hong Kong manufacturing facilities quickly passed all supplier quality audits, and we proceeded to mass production ramp-up within the tight cost controls mandated by the customer. 

STAGE 2

Testing and validation

• After co-developing the specifications, assembling and testing several prototypes, we proposed a solution that would meet 90% of the past generation’s mechanism performance. 
• We had to be flexible and improve the design halfway through the project to meet some specifications that had evolved.
• Our motor engineering expertise combined with our commitment to technical diligence, enabled our engineers to re-design, re-validate and manufacture a new mechanism assembly. 

STAGE 3

Precision manufacturing

• The customer had insufficient expertise in Asian manufacturing to be able to deliver this project without our trusted support.
• In order to meet their quality criteria, we created bespoke serialised line-end testing equipment to store tests results for every mechanism made.
• This ensured ultimate quality control and product traceability. 
• Detailed planning, lifecycle management and statistical control processes, enabled us to manage their risk, and deliver on time and to spec.