Applications 3d: Reverse Engineering, Surface Modeling Dies and Molds

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3D Scanning

A local mold making company in Windsor was faced with the challenge of modifying a mold for a vacuum cover. The real problem was that the mold had been manufactured by another mold making company and the original data was not provided with the mold.

Applications 3D was called in to do 3D scan of the mold and come up with the required math data so that the needed modifications could be performed on the mold. The 3d scanning was performed at the customer’s location on the shop floor. This was possible with Applications 3D‘s mobile and portable digitizing equipment. Since the scanning does not require any reference points to begin with, there was no fixturing of the mold on a reference or granite plate. The whole measurement was completed within a few hours.
The scan data was then moved into a coordinate system using captured guiding information like guide pins and holes from the mold . The relevant areas were then converted from measured xyz points to surfaces. The finishes IGES surface data (also called math data) was finally used to cut and modify the mold using CNC machining. After it was polished and textured the mold was ready to produce the new and improved component!!

Inspection

Car headlights aren’t as simple as they appear to be. There is a lot of engineering involved behind their manufacturing, so that they result in pleasant looks as well as attain the required light handling and reflection properties. Since the light flashed from a car’s headlights has to illuminate far away objects in the path of the car, there is extensive testing done on the light reflection properties of the headlight. The headlight consists of an injection molded part which adds to the problem of producing an accurate final part due to the inherent shrinkages and other variables in the molding process. This means the mold has to be near perfect and conform with the design intent within the required tolerances. The mold is dimensionally inspected, and tolerances of two thousandths of an inch are used to decide if the mold is usable or not. Conventional CMM machines do not generate enough measurement points to provide a complete picture of the whole mold. So, they are generally measured by optical scanning systems.

Applications3D was called in to do such an inspection on an automotive headlight optics mold insert. Since the project was “hot”, it meant that the measurement had to be completed on the weekend at the customer site. The measurement was to be done with a white light scanner with the highest accuracy and resolution so that the complete mold was scanned with no reflective area of the mold remaining unmeasured. This was achieved using the state of the art Steinbichler Comet 75 scanning system. This system consistently achieves accuracies of less than one thousandths of an inch for each measurement. Since this system uses white light as a modus operandi, the mold insert was coated with a micro thin layer of a reflective material. This material is not damaging to the part and can be wiped off with a cloth. The scan was completed on time, resulting in millions of points on the surface of the mold.
This scan data was then compared with the original CAD file of mold, the same file which was used to manufacture the mold. The results of the inspection were provided to the customer in the forms of easy to read color plots which represented each area on the mold with a different color based on how much it was out of tolerance. The in- tolerance areas were shaded grey for easy identification. As well, old fashioned, text reports were also generated for those familiar with CMM type reports. The mold insert was found to be significantly different than the CAD data (or the math data), thus requiring extensive modifications to the mold to conform to the required tolerances.

Molds and Dies

One of our prestigious customers, a mold making company, had a small dilemma. Their customer, who is a plastic chair molder/manufacturer, wanted a special mold for a plastic chair that included the Texas map on it as well as a series of patterns and a rose shape on it. Since the cost of such a mold is substantial, they wanted to build just one insert which could be changed in the mold, so that the mold could become multitasking and produce more than one kind of chair. On top of it, they had just provided a handmade sketch for the mold insert. An ideal art to part strategy was employed to handle the situation. That sketch was used as a basis by an experienced patternmaker to make a full scale clay model that represented the actual mold insert with the proper dimensions to fit in the mold.

Applications 3D was hired to reverse engineer the clay model into a high quality, workable CAD file. The first step of the reverse engineering was to do an accurate 3d Scanning or digitizing of the model. This was achieved using state of the art Steinbichler Comet 75 white light scanning system. Since this model contained some very fine features, the Comet 75 was an ideal machine to digitize it. The Comet 75 measures 420,000 xyz points in a 2 inch by 3 inch area. That meant a lot of points were to be collected over the whole model. After the scanning was completed, the scan data was processed to form into an STL file, which essentially is a large mesh of 3 sided polygons or triangles. During this process, the data was optimally reduced or “decimated “ to intelligently reduce the number of points on the planar areas and keep a high number of points at the areas of high curvature or small features. This whole process was done on Polyworks, a state of the art point processing software.
The STL file was then used to manually convert each feature and shape into a high quality, high accuracy surface. This engineering grade surfacing was performed on Imageware, one of the world’s best freeform surface modeling tools. Not only did the surface model look good, it also conformed to the stringent accuracy and continuity requirements of the downstream mold designing and machining softwares. The IGES surface model was used to program the cutter paths for the CNC machines and was eventually used to machine the insert successfully by our customer. It fitted well in the mold and is now mass producing the custom chairs!

Reverse Engineering

One of the biggest power generation systems manufacturers in North America wanted to design a new manufacturing process to produce steam turbine buckets. Since it was a tryout process and the old turbine buckets were made by a different process, the old turbines were 3d scanned to generate the math data for them. After the scanning was done, the data was then manually converted to a high quality industrial grade surface model which was further converted into an IGES solid model to use as a basis for CNC machining. The machining was performed in Germany by a well known CNC machine manufacturer. The machining was done from a whole block of steel since the turbines do not have any joints or welds in them. Since the solid model was already generated, it was easy to analyze and modify on the computer. This process proved to be a viable solution for manufacturing turbines in mass scale, saving time and resources in the long run.
Apart from this , different inspection reports for the manufactured turbines can be generated: