With plastics making up half of vehicles today – and set to grow to 75% of vehicle weight by 2020 – the need to manage design challenges, production efficiency, and quality in a uniform digital environment has never been greater.

By integrating part inspection and analysis with computer tomography (CT) scanning systems, manufacturers of plastic automotive parts can enhance the economics of molding via direct costs (yields, speeds, labor), along with lowering warranty and service expenses for original equipment manufacturers (OEMs) and their supply chains.

CT is not a new approach, however, software that interprets CT data has made significant strides in accurately comparing manufactured parts to original computer-aided design (CAD) data, providing rich insights into issues of geometry compliance, tolerancing, porosity, mold design, and fiber orientation.

CT-scan data allows software to color-code visualization of deviations of the manufactured part. Output CAD elements can correct tools for injection molding and casting or geometries for 3D printing.

Lightweighting

The automotive industry is at the forefront of lightweighting, and in the quest for lighter, stronger parts, the industry is experimenting with plastics – adding porosity and fiber to produce innovative shapes that expand functionality and performance. Those efforts exacerbate the traditional, familiar challenges of working with plastics, such as predicting shrink rates, flow, and cooling and then verifying final part dimensions.

Post-manufacturing comparisons of actual part dimensions and tolerances to the original CAD model is the first priority for engineers. Today’s integrated computer-aided mold and part design is a very mature science, however there is still a black art involved in pushing design boundaries for unusual shapes and meeting other demanding performance and cost goals.

Integrating CT into part inspection can address some concerns by anticipating production challenges early in the design phase. CT analysis software conducts high-fidelity structural analyses to guide geometry correction for molds and tool cutting and to improve production settings.

A CT-scanned object compared with its CAD data set allows for geometric comparison of voxel, mesh, and CAD data.

Part development

Assigning tolerances to material choices requires an understanding of behaviors in the molding process and the potentially harsh environments that products face once released. Advanced CT software addresses the most challenging, impossible-to-access surfaces, such as internal structures, and captures tolerances while checking mating specifications for assemblies and part interfaces.

When making test parts and soft or hard tooling, software provides critical feedback on various deviations from wall thicknesses to warpage. Third-party CT analysis software can streamline the typically lengthy debates between parts designers and toolmakers that occur when determining whether designs or molds need rework. Hard data gained from measuring internal surfaces can eliminate the guesswork in rooting out the sources of flaws.

Modern tools

Accuracy, user friendliness, and visualization are key to CT evaluation software packages, simplifying first-article inspection for nominal/actual part comparisons. In follow-on, repeat scans of individual production runs or batches, software can quickly confirm constant production quality.

Scanned data are imported into analysis software and compared to the master CAD model in an overlay that highlights the nominal range of accepted tolerances, deviations, and faults against the real-world geometry. Color plots make digital comparisons and call-outs instantly noticeable. Teams can then consider corrective actions to the model or mold to meet the desired specification using definitive data instead of assumptions and black art. Manufacturing correction technology then automatically adjusts geometry in the mold or CAD model.

High-fidelity analysis software reveals geometric complexity more accurately than tactile measurement approaches. Designs can be digitally divided into prioritized regions of interest (segmentation), saving analysis time. Destructive testing is unnecessary: the software reveals porosity, external and internal, as well as otherwise impossible-to-access hidden areas of concern such as passageways, weld zones, cracks, voids, sinks, and density changes.

Simplified processes

Advanced software automates a substantial amount of the interaction previously required between inspection and CAD geometry, CAD product manufacturing information (PMI), simulation, and manufacturing (molding, casting, cutting, and additive manufacturing).

Beyond proving quality in finished plastic parts, high-fidelity CT analysis can support advanced lightweighting techniques in porosity-induced plastic designs, evaluate fiber strategies used for strength, and encourage creation of innovative geometries that improve automotive ventilation, aerodynamics, and aesthetics.

Volume Graphics Inc.
https://www.volumegraphics.com