The standard design of microscopes has always been functional and utilitarian. So when
leading optical group Carl Zeiss revamped its range of EVO Scanning Electron
Microscopes (SEM), it decided to inject some clear styling to improve the aesthetics and
enhance the high end brand positioning of the products.

The German company used DesignEdge, a Cambridge-based industrial design and
engineering agency, to work on the EVO project. DesignEdge won a Design Week
Award last year for an intelligent home security system it designed called AlertMe.

“All too often, design has been an afterthought behind function, technology and price,”
says DesignEdge co-director Bruce Hutchinson. “That’s changing as manufacturers see
design as a way to offer a real point of difference. Eye-appeal can affect purchasing
decisions and, furthermore, design can play a big part in usability and even bring costs
down through the right choice of materials and manufacturing techniques.”

The initial phase saw DesignEdge using digital sketching tools to accelerate the concept
development process. SolidWorks was then used to produce fully-detailed production
drawings and high quality rendered visuals for client review.

The design for the new EVO range is complex and DesignEdge recognised that the
manufacturing process would also be challenging. It turned to Midas Pattern Co of
Bedford as it was already familiar with its proprietary MRIM composite resin tooling and
production moulding system.

Hutchinson says: “The main microscope cover is a complex, large, deep component,
which combined with volumes in the 100’s per year make it very well suited to MRIM.”

Following approval from the client, Midas Pattern was able to provide tooling and parts
for three mouldings supplied in suites to meet the requirements of different sizes of
microscope. First, a product intent-to-CAD model was made for the three moulded parts:
the main cover, a smaller front nose cover and a cable guide side arm.

Midas Pattern then advised on any concessions required that would give benefits such as
manufacturability, cost, rigidity or ease of assembly. There was a cost advantage in
designing a single moulding for the main cover, but that can have a challenging knock-on
effect if using conventional tooling.

“Fortunately, the beauty of the Midas process is that it is possible to have undercuts, side
actions, square faces, moving cores, metal inserts and fixings at angles, without adversely
affecting tooling cost,” says Hutchinson. “The same is not true of conventional injection
moulding where tooling is very expensive and as a result, complexities should be
designed-out where possible.”

Midas Pattern says: “MRIM allows the most complex of mould tools to be made, in the
shortest of lead-times, using a blend of laminated and cast resins that incorporate areas of
CNC machined aluminium and steel.”

Tools made using the technology are guaranteed up to 5,000 parts, it says.
Some of the other manufacturing challenges faced by Midas Pattern on the EVO project
involved maintaining a tolerance of 0.5mm on the main cover height, principally because
the central microscope chamber moves vertically on bellows to absorb vibration. Also, as
the design was scaled to three different sized machines in the EVO range, modular
tooling was required to allow parts to be extended easily while keeping costs to a
minimum.

The versatility of MRIM tooling means that prototypes are often unnecessary.
Hutchinson says: “In the case of EVO it was apparent that the inclusion of some
additional stiffening of the main cover was desirable due to its size. After a brief
consultation we added some more fixing bosses and stiffening webs to the rear of the
solid polyurethane cover and Midas handled the rest.”