3D Model Surface Preparation for Laser Scanning
Customers can reduce the cost of laser scanning by doing their own surface preparation.
The ZScanner 800 (Creaform EXAscanner) is a versatile scanner capable of .2mm resolution and up to .04mm accuracy. One drawback to this scanner is that it is sensitive to surface color and specularity. Colors like red and black are difficult to scan and highly reflective surfaces can be impossible to scan. Proper surface preparation can improve feature detection, scanning speed and scanning accuracy.
The ideal surface for scanning is smooth, white and matte. As colors get darker, scanning speed decreases; a black surface can take 4 or 5 times as long to scan as a white surface. As surfaces get more specular (shiny), scanning noise increases; a highly reflective surface is all noise and no signal making it impossible to scan. And the scan data is always rougher than the surface, as surfaces get rougher, it becomes harder and harder to resolve features.
Of course, before any surface preparation can be done, the part to be scanned must be thoroughly cleaned and dried. Once this is done, the surfaces can be prepped in 1 of 4 ways:
1. Painting
Painting is the method of choice. Aerosol paint is relatively easy to apply and covers well. For scanning accuracy, Krylon Gray Primer is best. For scanning speed, Krylon Flat White works well. Whichever is chosen, the paint should be applied as thinly and as evenly as possible. Usually .0006" to .0010" is plenty. Of course the paint thickness alters the scanning results, but the results can be offset in software by the paint thickness, which will cancel out the paint thickness. But only one thickness value can be entered so it’s important to keep the thickness uniform.
Of course paint can only be used on parts that you don’t mind being painted or which are sturdy enough to hold up to removing the paint. Methyl Ethyl Ketone (MEK) will remove paint easily, but will damage many surfaces and dissolve some plastics. Be sure to read the safety precautions on the MEK container before using.
2. Powder Coating
An aerosol powder like Magnaflux SKD-S2 can be applied much like aerosol paint. The difference being that the powder is easily removed by rinsing, brushing or blowing off with compressed air on most surfaces. The powder is diatomaceous earth, which are essentially tiny silicon crystals. It’s nearly impossible to get out of porous materials and it can be very abrasive making it a poor choice for mechanical assemblies and mechanisms. The propellant can also slightly alter some finishes, especially painted surfaces and plastics.
Being easy to remove also means having to handle the part with extreme care. Even the slightest bump or breeze can knock off the powder.
3. Waxing
For high quality painted surfaces or plated surfaces, a light coat of paste wax works pretty well. Just apply the wax and let it dry to a haze. The thicker the better, but I’ve scanned chromed handle bars with only a very light coat of wax. Once the part has been scanned, just wipe/polish off the wax.
While this method works, the scanning rate is usually much slower than with paint or powder.
4. Replicate Casting
Replicate casting is used when the part is too complex for wax and too important or too delicate for paint or powder. Special low shrink silicone rubber is used to make a negative of the part and then the negative is scanned instead of the part. This method is also used to scan internal features that the scanner can’t normally "see".
Replicate casting can significantly increase the time and cost to process a part and is usually the method of last resort.
Not all surfaces require preparation prior to scanning. But for surfaces that do require it, customers can save money by doing as much of the preparation as possible.
Thursday, July 12, 2012
Sunday, April 15, 2012
3D Model Laser Scanning Multiple Times
3D Model Laser Scanning Multiple Times
Scanning a part multiple times can significantly increase the accuracy of the finished model.
A customer needed to reproduce some inserts for an automotive injection mold. Attempts to build them using their customer's CAD models failed because the inserts didn't match the models.
The inserts had advanced surfaces that had to match exactly with neighboring surfaces in the mold. This made the project ideal for laser scanning except that the accuracy required was about twice that of what my laser was typically capable of using a single scan. By scanning the inserts four times each and then averaging the scans, we were able to achieve the desired accuracy.
In a measuring system, if the measurement error is randomly distributed about zero, measurement uncertainty can be reduced as a function of the square root of the number of measurements made and averaged. In other words, if you measure something four times, the average of those measurements will have half of the uncertainty of any one measurement.
As part of Reverse Austin's monitoring of laser performance, I periodically scan and measure a CMM training standard. From the many measurements I've done, I can see that the measurement error is random and fairly well distributed about zero. If I chart the error from the averages of any four consecutive scans, I get errors that are a little less than half of the errors from individual scans.
If you've done your homework and you know the uncertainty of your scanning system, you can significantly improve accuracy (reduce uncertainty) by scanning multiple times and averaging the scan data.
Scanning a part multiple times can significantly increase the accuracy of the finished model.
A customer needed to reproduce some inserts for an automotive injection mold. Attempts to build them using their customer's CAD models failed because the inserts didn't match the models.
The inserts had advanced surfaces that had to match exactly with neighboring surfaces in the mold. This made the project ideal for laser scanning except that the accuracy required was about twice that of what my laser was typically capable of using a single scan. By scanning the inserts four times each and then averaging the scans, we were able to achieve the desired accuracy.
In a measuring system, if the measurement error is randomly distributed about zero, measurement uncertainty can be reduced as a function of the square root of the number of measurements made and averaged. In other words, if you measure something four times, the average of those measurements will have half of the uncertainty of any one measurement.
As part of Reverse Austin's monitoring of laser performance, I periodically scan and measure a CMM training standard. From the many measurements I've done, I can see that the measurement error is random and fairly well distributed about zero. If I chart the error from the averages of any four consecutive scans, I get errors that are a little less than half of the errors from individual scans.
If you've done your homework and you know the uncertainty of your scanning system, you can significantly improve accuracy (reduce uncertainty) by scanning multiple times and averaging the scan data.
Saturday, March 17, 2012
3D Model Laser Scanning for Molding and Casting
3D Model Laser Scanning for Molding and Casting
Laser Scanning can have big payoffs for Molders, Mold Makers, Foundries and Pattern Makers.
1. Faster mold qualification with fewer development cycles, especially for overmolding.
2. Reuse of existing geometry from previous projects.
3. Precise capture of customers' prototype geometry.
4. Protection of legacy tooling.
Instead of relying on a few gauge points, laser scanning captures the entire part. By comparing the scan data to the nominal CAD model, the amounts and locations of all deviations can quickly be determined. When correcting overmold problems, the scan data can be used to create solid (CAD) models of the parts going into the overmold tooling. These models can be used to modify the overmold tooling to provide precise matches and/or crushes to eliminate shutoff failures.
When building new tooling to replace or supplement existing tooling, like going from single cavity to multi cavity, laser scanning can be used to create accurate CAD models of the existing tooling. The models can then be used to machine molds, electrodes or patterns. When the new tooling is complete, it can be scanned and the scan data compared to the original scan data to confirm that the new tooling precisely matches the old.
Customers don't always have complete CAD models for their products; they may only have hand made prototypes or they may have machined parts with hand made modifications. Laser scanning can be used to create accurate high quality CAD models that can be used to machine molds, electrodes or patterns. Before any tooling is built, the CAD models can be used for Additive Manufacturing (rapid prototyping) to produce models for customer approval.
Many shops have tooling that predates their current CAD system. Even if compatible CAD models exist, the models may not include all the "tweaks" that were done to make the tooling perform. Laser scanning can capture the existing geometry including any tweaks. The scan data can be stored as STL for later use or it can be used to develop compatible CAD models. In the case of a catastrophic event, tooling can be rebuilt.
Laser scanning can be a cost effective tool with large ROI. Contact me and let me explain how.
Laser Scanning can have big payoffs for Molders, Mold Makers, Foundries and Pattern Makers.
1. Faster mold qualification with fewer development cycles, especially for overmolding.
2. Reuse of existing geometry from previous projects.
3. Precise capture of customers' prototype geometry.
4. Protection of legacy tooling.
Instead of relying on a few gauge points, laser scanning captures the entire part. By comparing the scan data to the nominal CAD model, the amounts and locations of all deviations can quickly be determined. When correcting overmold problems, the scan data can be used to create solid (CAD) models of the parts going into the overmold tooling. These models can be used to modify the overmold tooling to provide precise matches and/or crushes to eliminate shutoff failures.
When building new tooling to replace or supplement existing tooling, like going from single cavity to multi cavity, laser scanning can be used to create accurate CAD models of the existing tooling. The models can then be used to machine molds, electrodes or patterns. When the new tooling is complete, it can be scanned and the scan data compared to the original scan data to confirm that the new tooling precisely matches the old.
Customers don't always have complete CAD models for their products; they may only have hand made prototypes or they may have machined parts with hand made modifications. Laser scanning can be used to create accurate high quality CAD models that can be used to machine molds, electrodes or patterns. Before any tooling is built, the CAD models can be used for Additive Manufacturing (rapid prototyping) to produce models for customer approval.
Many shops have tooling that predates their current CAD system. Even if compatible CAD models exist, the models may not include all the "tweaks" that were done to make the tooling perform. Laser scanning can capture the existing geometry including any tweaks. The scan data can be stored as STL for later use or it can be used to develop compatible CAD models. In the case of a catastrophic event, tooling can be rebuilt.
Laser scanning can be a cost effective tool with large ROI. Contact me and let me explain how.
Tuesday, March 13, 2012
3D Model Restless Legs and BPA
3D Model Restless Legs and BPA
Eliminating BPA from my diet appears to have made a significant improvement in my RLS symptoms.
Essentially all canned foods and beverages contain BPA as do foods and beverages stored in containers made of polycarbonate (recycle code 7). A recent Harvard study showed that eating canned soup five days in a row raised BPA levels in urine almost 1300%.
For years, I've suffered from RLS. Recently, the symptoms became so severe that they were affecting my ability to work. After reading about the Harvard study and, separately, about a possible link between BPA and RLS, I decided to eliminate BPA from my diet; no canned foods, no canned drinks, nothing stored in plastic containers with a recycle code of 7. Also, no restaurant foods that may have canned origins like tomato sauces.
The change in my RLS symptoms has been dramatic. While there is no scientific proof that eliminating BPA helps RLS, it's something that's easy to do. For me, it has been well worth the effort.
Eliminating BPA from my diet appears to have made a significant improvement in my RLS symptoms.
Essentially all canned foods and beverages contain BPA as do foods and beverages stored in containers made of polycarbonate (recycle code 7). A recent Harvard study showed that eating canned soup five days in a row raised BPA levels in urine almost 1300%.
For years, I've suffered from RLS. Recently, the symptoms became so severe that they were affecting my ability to work. After reading about the Harvard study and, separately, about a possible link between BPA and RLS, I decided to eliminate BPA from my diet; no canned foods, no canned drinks, nothing stored in plastic containers with a recycle code of 7. Also, no restaurant foods that may have canned origins like tomato sauces.
The change in my RLS symptoms has been dramatic. While there is no scientific proof that eliminating BPA helps RLS, it's something that's easy to do. For me, it has been well worth the effort.
Wednesday, February 29, 2012
3D Model Reverse Engineering for Reshoring
3D Model Reverse Engineering for Reshoring
Laser scanning based reverse engineering is a powerful tool for reshoring.
It's sad, but true that many products being manufactured overseas were at least partially engineered overseas. It's very common for molds and tooling for US products to be designed by and be owned by overseas manufacturers.
The overseas manufacturers often develop and build tooling at "no cost" which makes it easier to get started, but nearly impossible to leave. If a customer wants to move a manufacturing operation, he or she is often faced with having to redesign and rebuild all of the tooling. Laser scanning can help.
Often the tooling development process results in small tweaks to the part design. And often these tweaks go unnoticed and don't get incorporated into the official design. Trying to build new tooling doesn't just involve redesigning the tooling, but also redesigning the part. And that's where laser scanning based reverse engineering comes in.
3D laser scanning (or X-ray CT scanning) can collect enough measurement data to completely describe a part. The scan data can then be processed with advanced reverse engineering software, like Rapidform, to create high quality, dimensionally accurate CAD models. These models can be used for designing tooling, design documentation and quality control.
Think about laser scanning the next time you're involved in a reshoring effort.
Laser scanning based reverse engineering is a powerful tool for reshoring.
It's sad, but true that many products being manufactured overseas were at least partially engineered overseas. It's very common for molds and tooling for US products to be designed by and be owned by overseas manufacturers.
The overseas manufacturers often develop and build tooling at "no cost" which makes it easier to get started, but nearly impossible to leave. If a customer wants to move a manufacturing operation, he or she is often faced with having to redesign and rebuild all of the tooling. Laser scanning can help.
Often the tooling development process results in small tweaks to the part design. And often these tweaks go unnoticed and don't get incorporated into the official design. Trying to build new tooling doesn't just involve redesigning the tooling, but also redesigning the part. And that's where laser scanning based reverse engineering comes in.
3D laser scanning (or X-ray CT scanning) can collect enough measurement data to completely describe a part. The scan data can then be processed with advanced reverse engineering software, like Rapidform, to create high quality, dimensionally accurate CAD models. These models can be used for designing tooling, design documentation and quality control.
Think about laser scanning the next time you're involved in a reshoring effort.
Saturday, February 11, 2012
3D Model Texas Medical Device Alliance and STL
3D Model Texas Medical Device Alliance and STL
I attended my second TMDA meeting on February 9, 2012. The presentation by David K. Leigh was especially interesting.
David spoke on the evolution of design and manufacturing and the role of additive manufacturing in the evolution. He also spoke of the need of and ongoing efforts to develop formal specifications for additive manufacturing processes.
Later, via email, David pointed me towards information on the ongoing development of a replacement for STL. Originally dubbed STL 2.0, it's now named AMF. The format promises to significantly increase resolution while simultaneously reducing file size. Additionally, there are discussions on adding the ability to include voxel data (3D bit-maps) commonly used by medical imaging equipment and industrial CT scanners.
David K. Leigh is the president of Harvest Technologies in Belton, Texas.
I attended my second TMDA meeting on February 9, 2012. The presentation by David K. Leigh was especially interesting.
David spoke on the evolution of design and manufacturing and the role of additive manufacturing in the evolution. He also spoke of the need of and ongoing efforts to develop formal specifications for additive manufacturing processes.
Later, via email, David pointed me towards information on the ongoing development of a replacement for STL. Originally dubbed STL 2.0, it's now named AMF. The format promises to significantly increase resolution while simultaneously reducing file size. Additionally, there are discussions on adding the ability to include voxel data (3D bit-maps) commonly used by medical imaging equipment and industrial CT scanners.
David K. Leigh is the president of Harvest Technologies in Belton, Texas.
Wednesday, January 11, 2012
3D Model Reshoring with Laser Scanning
3D Model Reshoring with Laser Scanning
Laser scanning can be a vital tool in bringing manufacturing back to the US.
A customer of one of my clients wanted to reshore a line of fishing lures. Production was continuing overseas so the molds were not available. Also, due to the high level of rework required on the lures, it was felt that the overseas molds would not be adequate for US production. My client's customer chose to have new molds built here.
My client, an injection molding company, had already begun production of one lure in the series. Reverse engineering the first molds using conventional methods was very time consuming and required several mold revisions to achieve an acceptable product. Repeating the process on the other lures in the series was going to be prohibitively expensive so Reverse Austin was contacted to see if the process could be expedited using laser scanning.
My client had had less than satisfactory experience with laser scanning performed by a previous vendor. The CAD models produced were comprised of many small surface patches that included small imperfections and which were difficult to tool path.
To show my client that not all laser scanning is created equal, I grabbed an old lure from my tackle box and scanned and modeled it. Based on the results, my client agreed to have me scan and model two of the remaining lures in their customers line.
My client had SLA rapid prototypes made from the Reverse Austin CAD models
Laser scanning can be a vital tool in bringing manufacturing back to the US.
A customer of one of my clients wanted to reshore a line of fishing lures. Production was continuing overseas so the molds were not available. Also, due to the high level of rework required on the lures, it was felt that the overseas molds would not be adequate for US production. My client's customer chose to have new molds built here.
My client, an injection molding company, had already begun production of one lure in the series. Reverse engineering the first molds using conventional methods was very time consuming and required several mold revisions to achieve an acceptable product. Repeating the process on the other lures in the series was going to be prohibitively expensive so Reverse Austin was contacted to see if the process could be expedited using laser scanning.
My client had had less than satisfactory experience with laser scanning performed by a previous vendor. The CAD models produced were comprised of many small surface patches that included small imperfections and which were difficult to tool path.
To show my client that not all laser scanning is created equal, I grabbed an old lure from my tackle box and scanned and modeled it. Based on the results, my client agreed to have me scan and model two of the remaining lures in their customers line.
My client had SLA rapid prototypes made from the Reverse Austin CAD models
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