Well, ideally, you have a machine that can mill the clay to help sculpt the design and bring it to life. Some components to consider are the base of the machine itself, the carriage system, the milling head, and a laser line scanner to create a point cloud so the design can be 3D scanned and turned into a model. I am not going to cover the entire operation, one of my colleagues is writing about that, I am just going to concentrate on the technical apparatus that you will encounter.
So you have a base plate that is either flush with the floor, or that is raised. If the plate is in the floor, it will have the carriage system attached to rails underneath the floor and covered with plates. It the plate is raised, the carriage will be attached to rails on the side of the plate. There are advantages to both setups depending upon your existing spaces.
Next you have the carriage. The carriage needs to be sturdy and accurate enough to both carry out the milling operations and in turn, be able to pick up a laser to scan any changes and incorporate them into the 3D model. This is typically called an arm on a machine that is called a horizontal arm. You will have a column and the an arm extending into the working volume.
In some cases, you can have multiple arms on the same side or even multiple arms on both sides. Obviously, the controller and underlying software has to take into account for the positioning of these columns and arms accurately, as well as, keeping track of every arm position within the volume. The controller basically plays traffic cop and operation manager at the same time.
The head(s) of the class
The plate and arms however, are not the stars in this show. The milling head and laser scanner are. Imagine the following scenario: After a quick tour of an existing design, the lead decides to reshape a rear quarter panel. He or she then leaves expecting the modellers to mirror this change on the opposite side, as well as to update the 3D Model.
That’s where the scanner and milling head combination shine. The operator tells the machine to scan the new changes and mirror them on the model. In this example, the machine moves to the desired area, scans the are, inserts it in the model, then picks of the milling head to do the prescribed changes. This marriage of these two disparate activities is our advantage.
The laser line scanners, is just that, a series of laser lines that create a point cloud of the measured area. How is this accurate though? The whole system is built around that foundation. The base of the machine has scales that give a precise position of the column along the plate or table.
In turn, there are scales on the column which indicate the Z height of the arm, and scales on the arm itself, to determine how far it is moving in the volume. Remember we talked about the controller? The controller is keeping track of all of this, records all of these positions. The software uses this information to collect the new data and tie it to the existing model. The software then tells the controller to pick up the milling head and have the milling head carry out the modelling sequence to match the feature to be mirrored.
This is not your kids doh!
A significant part of Car Design is the clay because it is the physical manifestation of someone’s creative concept.
A quick note, one of the great things about this job, is that you come across very nice people that are willing to help educate you on different topics. Mark was nice enough to reach out and supply this information for this blog. You can find Mark at: http://www.claywarehouse.com/
Clay Warehouse Inc.
“Thought the attached might help with regard to your blogger. Basically hand modelers want a clay that packs well onto the foam model and stays warm long enough to pack a full sized model then cools evenly for smooth surfaces and crisp edges. They like a clay that sticks to itself really well but not to the tools too much or the model when sculpted. They want to make repairs easily either using a small piece of clay out of the oven (usually heated to around 150F) or be able to warm some up in their hands, kneading it then pushing or smearing onto the surface and be able to use their tools on that area without the clay popping off. There cannot be air bubbles in the clay or it will show up on the surface.
Over the last ten years most studios have switched from a sulfur based clay to sulfur free. This was primarily because new computer circuit boards have a silver compound for soldering instead of lead based solder. When the sulfur based clay was heated it would release sulfur into the air and it attacked the silver causing corrosion.
As you can imagine this was a huge problem for the design studios. The switch from sulfur based to sulfur free has not been easy for the design studios because they were used to the characteristics of the sulfur based clay however there was many advantages. Sulfur free clay is around 40 to 50% lighter than sulfur based helping with everything from large overhangs on models to lower shipping costs.
Sulfur free clay is much more homogeneous whereas sulfur based clay could have ‘chunks’ or ‘boulders’ of sulfur that when a sculptor dragged a steel slick over the surface would cause a major flaw that needed time consuming repair.
Sulfur free clay costs more per pound but a pound of sulfur free clay covers around twice the area of sulfur based so the cost is off set although this is difficult for modeling departments especially accounting to understand.
Clay models are often put outside for ‘walk around’ showings after having modeling film or DiNoc applied to simulate a painted model. The clay also has to withstand drastic temperature changes going from an air conditioned studio into a hot courtyard under direct sunlight then back inside.
So in a way, the clay almost has to be a miracle material. It has to get soft in the oven but not too soft and not get too soft in the sunlight. It has to be soft enough to apply and sculpt but be hard enough for proper milling and detailed edge, line definition when sculpting. Also it needs to be something that will work well in the wind tunnel.”
When I communicated with Mark, he let me know that he had partnered with AMACO to produce such a clay that would meet all these specifications. You can get more details by contacting Mark directly. The following is from information he provided.
“AMACO MI Industrial Styling Clay adheres to all normal armature materials. AMACO MI Industrial Styling Clay may be shaped manually or via CNC milling machines. Product formulation will provide a very smooth finish with less milling clean up passes. Super fine amounts of material may be steeled or tooled away. Formula produces less sticking to floors and tools. AMACO MI Industrial Styling Clay polishes excellently.
At room temperature AMACO MI Industrial Styling Clay will remain pliable without hardening and cracking. Surface details will retain crisp edges. If large areas need repair or alteration, warm that area so that the new material will bond perfectly with the original surface. (This will promote cohesion rather than adhesion)
AMACO MI Industrial Styling Clay is manufactured by American Art Clay Company in Indianapolis, Indiana ‐ United States of America.”
Interested in more information? Click on this link t to ask us a question.