Innovative 3D optical measurement specialist uses NX to create and manipulate digital representations

From physical to digital

“Accurate 3D measurement of precision products.” That’s how Tim Rapley, founder and chief executive officer (CEO) of Physical Digital® Ltd (Physical Digital) describes the capability of his company, which transforms physical objects into digital form. By creating a digital twin of an existing item, Physical Digital uses the latest techniques to deliver faithful reproductions, rigorous inspections, optimized designs and manufacturing.

“Anyone can use a mobile phone to scan an object and gather digital data, but the key is to measure something accurately,” explains Rapley. What Physical Digital provides is dimensionally precise. This is particularly critical for some customers, such as those in the aerospace industry, which demands extremely high standards, traceability and auditing.

Since it was established in 2005, Physical Digital has grown via customer recommendations, and in 2017 it relocated to larger premises where it could accommodate the company’s ATOS ScanBox in an environmentally controlled measurement cell. Physical Digital also uses mobile scanning units for on-site measurement to service both national and international customers.

Combining photogrammetry and 3D structured light scanning

The company serves a wide variety of customers, from hobbyists for a one-off personal project to large corporations with long-term, ongoing project requirements. “We can scan a minute item or an entire aircraft,” observes Rapley. “We’ve been commissioned by global aerospace and automotive companies, racing teams, prestigious jewelry designers and international filmmakers to carry out measurement projects, all with varying levels of requirements. We often have to work in complete confidence under nondisclosure terms.”

The company is frequently called upon to scan legacy components and heritage designs for which there is no 3D data. In these cases, the ability to reverse engineer is critical. Many customers are looking to inspect and analyze an existing component; for example, an original equipment manufacturer (OEM) might want to compare the parts delivered by different suppliers.

Physical Digital uses a scanning system that employs two cameras and a projector. The system calculates the exact position of optical markers, and uses a blue light-emitting-diode (LED) projector to project a phase-shifting fringe pattern across the object. The single wavelength blue light minimizes the effect of ambient lighting and cuts down the negative effect of reflection on shiny surfaces. The projection is captured by two high-speed cameras, which convert the images into millions of 3D points. Several scans can then be combined to capture a large area, and once processed, it can be exported as a stereolithography (STL) file.

Dan Lainchbury, engineering manager, comments, “Physical Digital chose to use NX from Siemens Digital Industries Software because it is vital to work with software that can comfortably handle our scan data and allow us to interact with customers across a wide range of industries.”

Using NX to reverse engineer

Design engineer Steven Kreczman describes how Physical Digital begins the reverse engineering process: “After inspecting the scan data file, an STL file is imported into NX. Here an initial CAD model, which is based on the scan data, is drawn up. If there is an original drawing, we can highlight any deviations between that and scan data, and models are deliv-ered to the customer’s specification as an as-measured model or a design-intent model.”

Surfaces are added to create a 3D model of the scanned item in NX™ software. Depending on customer need, the computer-aided design (CAD) model can be a basic shape or a complex parametric model that links all aspects of the design such as screws and holes. “The parametric modeling capabilities of NX are unparalleled,” states Kreczman. “If I need to make one change, it will cascade through the whole design and make sure that every-thing is aligned. It is therefore easy to handle complex designs for large assemblies, and I can save further time by using automated scripts.”

Once the 3D model is created, Physical Digital has complete freedom and flexibility to design features required for the manufacturing process; conduct finite element analysis (FEA) for validation and prepare drawings for manufacture and inspection. “In addition to all its functionality, the advantage of NX for our customers is the quality of models produced and the ease with which it interacts with other software,” says Kreczman.

Renovating a classic car

In one project, Physical Digital worked with a casting company that had been commissioned by Aston Martin to produce the cylinder head and block for the DB4, designed in the 1950s and produced in 1958. An original drawing was available, but without the patternmaking skills of a bygone era it would have been very difficult to manufacture it again. Analyzing the scan data revealed some areas that could be modified so when Physical Digital’s design engineers created a 3D model, they optimized the design as well as designed cores and tooling that were ready for casting. In addition, manufacturing drawings were produced for casting and each machining operation to facilitate computer-aided manufacturing (CAM).

Recreating hand-made geometry

When Scorpion Ribs, a high-end manufacturer of rigid inflatable boats, wanted to make a new tool for a boat hull, it turned to Physical Digital to recreate a historic design. “Historically, the marine industry would use hand-modified molds and tooling,” comments Kreczman. “However, we can add design intent such as symmetry, and will work from one side or average out both depending on the specification.”

The scanned data was imported into NX, and high-quality, parametric surfaces were produced. With a digital model of the original handmade tool, to go down the traditional route of hand building a plug, which would have taken up to 12 weeks. Instead, Scorpion Ribs was able to pass data directly to its supplier for immediate remanufacture.

Saving time and money with digitalization

Whether measuring a new vehicle design, inspecting an aerospace component or recreating a decorative frieze, Physical Digital enables companies to save time and money, often at a critical point in the development process. West Surrey Racing (WSR), a perennial championship-caliber British Touring Car team, saved two weeks of development time during a three-month period. WSR said this was a contributing factor to the team’s success in the 2017 season.

With expertise in geometry, emerging materials and new processes, Physical Digital educates customers about potential opportunities. “We have grown organically because we help our clients articulate what they are looking for,” explains Rapley. “We help them on a digital journey, and with reverse engineering we put them in a really good position to make further design improvements.

“We would not have won some projects without NX, and for some customers the use of NX is part of the requirement. Our use of NX is supporting business growth and we anticipate that our PLM tool will help us shape our future services.”