In early 2014, Spring srl — based in Monteviale, near Venice — decided to reverse-engineer components in-house instead of sub-contracting the work. After a thorough market analysis, the company bought a seven-axis CNC articulated measuring arm and a digital laser scanning head.

This equipment not only allows customers’ parts to be digitised quickly and accurately for reverse engineering and ‘3-D printing’, it also greatly enhances the capabilities of Spring’s quality control department.

Large parts as well as small ones can be measured using the portable MCAx arm and ModelMaker MMCx 3-D laser scanner from Nikon Metrology (www.nikonmetrology.com). This equipment was supplied by Leonardo 3D Metrology, Nikon’s Turin-based Italian reseller.

Roberto Toniello, Spring’s co-founder and head of its engineering department, says: “The Nikon equipment allows us to meet the needs and demands of our customers with greater efficiency, as we can now offer a comprehensive and accurate service in shorter lead times — and ensure maximum reliability of the results obtained.”

If Spring needs to reproduce a product but the CAD model does not exist or the original part has been modified, the company will reverse-engineer an actual component using the Nikon equipment. Spring then processes the scan data using Geomagic Studio software, which imports the raw point-cloud data and converts it into accurate surface, polygon and native CAD models.

These are then exported to one of Spring’s 10 CAD seats of Pro Engineer and Unigraphics NX, where STL files are generated for driving six Stratasys Fortus FDM (fused deposition modelling) additive-manufacturing machines. Two are large ‘3-D printers’ with build volumes of 900 x 600 x 900mm, making Spring one of a few Italian companies that can produce objects of that size by FDM.

Layer by layer

The machines produce components layer by layer from thermoplastic materials that range from standard ABS through weather-resistant ASA to Ultem 9085 — a flame-retardant material with a high strength-to-weight ratio that is certified for aerospace use. It is also suitable for marine, Formula One and other motor-sport applications.

Once parts have been built, they are inspected using the scanning equipment to determine their accuracy, using either the laser head or an interchangeable touch probe — or both. Software from Nikon Metrology provides the measurement and analysis capability, with intuitive tools for both laser and tactile scanning applications.

The quality control data is compared on-screen to the original CAD file, whether supplied by the customer or derived from reverse engineering. Any out-of-tolerance features are readily observable and measurable, and part-to-part comparisons are made to determine the reproducibility of a production process.

Nikon Metrology’s Focus Handheld software underpins these activities, managing the acquired point clouds, performing the comparisons, carrying out advanced feature inspection and producing reports. It is essential for Spring to control component quality closely, verifying the accuracy of parts and generating corroborative reports.

Aerospace and Formula One customers in particular require full traceability of production back to the raw materials, but it was difficult for Spring to provide that level of service before its in-house metrology capability had been enhanced.

Combined experiences

Spring was established in 1998 by Fabio Gualdo and Roberto Toniello to combine their mould and component design expertise with the emerging additive-manufacturing technology. They were among the first to recognise that this would allow mass customisation of products tailored to customers’ specific requirements as an alternative to mass production.

Today, the research, design and development bureau serves both ends of the market, manufacturing prototypes and batches of components by 3-D printing, while also designing and supplying moulds for plastic injection moulding and die casting for longer production runs.

Mr Gualdo says: “In series additive manufacturing, it is often necessary to optimise the design of a component. A piece originally intended to be made by chip removal frequently has to be completely re-modelled — especially if it is in a new material — to give it the required mechanical characteristics or to reduce weight.

"A good example is our recent manufacture of a helicopter part in the thermoplastic Ultem 9085, instead of the previously used aerospace-grade aluminium. Traditional manufacture required a lead time of four to six weeks and cost around 500 euros per piece. This has been halved by 3-D printing — and the time-scale has been cut by a third.”

Mr Gualdo also says that for the past few years, he and his colleagues had felt the need to offer customers the ability to produce more-complex parts. However, the firm’s manual measuring methods using traditional metrology equipment had significant limitations, hence the deployment of the Nikon Metrology digital scanning arm.

“The MCAx arm, unlike a co-ordinate measuring machine, is convenient to transport and allows us to examine all sizes of component we produce, up to the very largest. Moreover, the ModelMaker laser scanner has the versatility to inspect all of the thermoplastic parts we print in-house, as well as components we buy in that are made from a variety of materials. Other scanning systems we investigated were not able to process all of these materials.”

Scanning versatility

The lightweight ModelMaker laser scanner features adaptation of the laser source intensity, allowing any surface to be scanned without the need for spraying or other pre-treatment.

The unit also features enhanced sensor performance (ESP3), which avoids the operator having to manually tune parameters when scanning different surfaces — even those with varying colour, high reflectivity and transitions.

The unit, which also has a fast scan rate, offers a measuring accuracy down to 24µm, which is more than adequate for inspecting parts with typical drawing tolerances of 0.2mm. Moreover, the scanner has true non-interpolated resolution, allowing free-form surfaces and features to be scanned accurately and efficiently.

The laser stripe width is 160mm, and the density is 800 points over the stripe width. The MCAx arm on which the head is mounted is also lightweight, featuring a carbon-fibre tubular construction that is counter-balanced and thermally stable.

In conclusion, Mr Toniello said: “The laser scanning arm has made a big difference to our business. Previously, we would 3-D print a customer’s parts and out-source them for dimensional inspection. It took two to three days for the components and reports to be returned. Now, we use the Nikon Metrology scanning arm to check parts the same day as they come out of the FDM machine, allowing us to quote more-competitive prices and turn orders round faster.

“Similarly, we save time and money in other areas — inspecting tools, jigs and fixtures, for example, as well as plastic injection and die-casting moulds.”