Introduction
The thrust of today's market driven development of low-volume high-value scientific instruments, such as the DNA Analyser used in this case history, is just as vital as the forces driving the developments in higher volume consumer goods such as motor cars and vacuum cleaners. Cost of Development and the Time to Market are the common factors at the top of any designer's checklist.
The Chief Executive authorising the investment in a new product has probably lived through many such exercises in the past and recognises the benefits of:
- Top quality Industrial Design from concept to detail
- Time Compression where appropriate in the development programme
- Early revenue to pay back the investment in a new product
Boardrooms are beginning to brief Product Development teams that no longer is there any tolerance or indeed any technical requirement in today's product development programme for the luxury of - multiple prototypes- temporary tooling - "square-one" design revisions - retrospective concept reviews - and open ended budgets for the - "try it and revise it" philosophy which was so prevalent in the 1980s.
Even the process of RAPID PROTOTYPING (Stereolithography and it's variants) which generates computer-created models direct from CAD data, usually followed by a non-production "cloning" processes such as RIM into Silicone Tooling, is far from the complete answer to the issue of how manufacturers can achieve rapid and adequate volumes of -production quality, finished product delivered to the marketplace, so maximising early revenue.
Designers in conjunction with the Chief Executives of some of the newly emergent breed of Rapid Product Development Companies are well up to speed on the available technologies and the relevance of each to the development process. The best of these Management / Designer / Client teams will address the flow of funds and ideas holistically from concept through to production, mixing and matching the optimum technology for each stage, bringing a fully developed product to market at the earliest date.
The dream scenario, which is becoming the new "Holy Grail" of Rapid Product Development, is to move from virtual design, assembly and function assessment using powerful and sophisticated 3D CAD Systems directly to Market Ready Product in a single process step.
This objective was top of the agenda when Osborn Jones of the Manufacturing Operations Group of Snowdonia BIC together with Designer Alwyn Morus of CADARN visited us for the preliminary discussions which preceded the production of the DNA Analyser illustrated.
Note:
The MOG of Snowdonia BIC comprises an elite team of manufacturing practitioners providing specialised expertise in all aspects of product development. In the case of this project the responsibilities for the development of the product were split as:
UNIVERSITY OF BANGOR- Software & Control Electronics
CADARN- Mechanical, Chassis & Casework Design.
TECHPRO- Wiring harnesses to bring electronic components together.
PICOSORB- Project Management.
Product Design Brief
The AutoRELI 48 is part of a DNA analysis system designed for Dynal UK Ltd, (one of Europe's leading medical equipment suppliers) with the objective of fully automating and doubling the ability of the analyser to test and match the DNA of donors and recipients in potential transplant situations.(The previous unit was semi-automatic with a 24 well capacity for samples).
Within Dynal's marketing programme the need for this product was immediate and ongoing with medium term production forecasts in the low hundreds.
The design unit of the consortium- CADARN headed up by Alwyn Morus, in consultation with analytical specialists Techpro. Medical and Picosorb created the CAD renditions of AutoRELLI 48 in Mechanical Desktop and conceived a manufacturing philosophy which worked well in the final analysis as follows:
- Metal formings were to be used for the base, structural sides and the mounting for some of the heavier electrical components.
- The main chassis and lid had to be very precise structural mouldings acting as anchor points for the majority of the functional components. Reagent bottles, peristaltic pumps, motors and other components generated a multitude of critical interfaces.
- Of prime importance was the precision with which the automated pipette arm could index to each selected sample-well to deliver or remove reagent.
- The alignment and support system for the large and extremely complex chassis comprised three metal rods CNC located from wall to wall of the metal side cheeks. (Figure 2 shows the location of one of these in blue. Also visible is the RFI coating that was required to be applied to some parts of the chassis underside.) The moulding would pick up its datum from these rods.
- The lid moulding also had multiple functions carrying displays and a heater element. (Figure 3 with the lid closed shows the final effect.)
- Finally, moulded side cheeks enhanced the cosmetics and lid function. These carried large integrally moulded hinge pegs obviating the need for separate mechanical hinges.
Beyond the ability of any chosen process to meet the engineering precision, strength and quality requirements, it was considered imperative that
A) Without repeated or further tooling investment it must be feasible to proceed directly to medium volume production in one single step, and
B) Should design changes emerge in the transition from a CAD-Proven Virtual Model to the Market Ready Article they could be taken on board even post-launch without major expense or delay.
The Manufacturing Process
The product envelope of 700 X 600 X 550 mm itself is a daunting prospect to some processes used in Rapid Product Development and the added factors of precision and complexity would normally dictate expensive metal tooling and long time-scales both of which are an anathema to RPD.
Cellular Mouldings of Kettering however employ unique and intellectually protected methods of achieving just such results in Rapid Low-Cost Tooling. With over 200 clients, 20 years experience and the capacity satisfy 40 or 50 clients simultaneously in any month whether the requirement is for tight deadline product launches or for regular volume production Cellular Mouldings occupies a market leadership position having pioneered and developed the materials and the process they operate.
The starting point for a project can be:
A) CAD data in all popular formats
B) 2D drawings
C) Client's own model
D) Existing product for reproduction/ variation
In the case of the AutoRELLI project, Cellular Mouldings client wished to source and control the generation of an SLA model of the main chassis and Cellular Mouldings allowed the client to tap into its buying power in order to obtain good prices and service on the Stereolithography. (Cellular Mouldings do not regard the stereo model itself as a source of profit and charge only for the skilled work performed on it to create a workable pattern for the Cellular Mouldings process).
The cover and side cheeks which were less critical on time scale were modelled by Cellular Mouldings using traditional methods and these items joined the tooling programme, on schedule, later in the procedure.
The checked SLA of the chassis was used as a master-pattern and Cellular Mouldingscreated final, long-term-durable, production tooling, taking a few days only from approved model to first sample for evaluation. (Standard service for medium complexity items is 5 working days).
Mouldings produced by Cellular Mouldings are not regarded as prototypes (although indeed they can fulfil that function in a very economic manner) but as factory finished, market ready product.
Alternative processes such as RIM into silicone tooling are sometimes erroneously regarded as competitive but the cost of the frequent retooling which characterises that method does not occur in the Cellular Mouldings system.
The client experiences a once-only set up charge at the start of the project and unless major redesign occurs the product can run indefinitely. Minor revisions and even niche market variants can usually be introduced without incurring significant mould revision charges.
Project Status
The AutoRELLI 48 has now been successfully launched in the USA and production is due to start having avoided the multiple model/temporary tooling/ non-production prototype/ stages which used to occur traditionally in Product Development. Also, by using the Cellular Mouldings process it was found unnecessary to go to high-cost metal tooling in order to achieve the accuracy, repeatability and production capability that the product demanded.
The total product development time was 6 months and this was approximately one third of the time usually associated with a product of this nature and complexity. The combination of CAD, Rapid Prototyping (for the most complex model), Immediate Production Tooling (IPT from Cellular Mouldings) and the team's skills in Project Management enabled an ambitious launch deadline to be met. The original checklist used by Osborn Jones, Alwyn Morus and their consortium colleagues sums up the project succinctly:
- We needed maximum CAD design sophistication
- We needed to utilise the advantages of current technology and processes to the full.
- We needed short time-scales
- We needed a "right first time" work ethic both internally and from our suppliers
- We needed a flexible approach to the inevitable bumps on the road.
We believe we achieved all of these on this project.
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