2. Which parts of the Cybertruck are hot stamped?
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Ausmann: Tesla hot stamped the double-door rings. That was the first hot-stamped part that Tesla had ever produced internally at any of its plants.
3. What are some of hot stamping’s advantages over cold stamping? What are the challenges?
Ausmann: The advantages not only are [making very strong parts] for safety, but having a part that’s a lot lighter in the vehicle, too, to reduce vehicle mass. Reducing weight used to be the big thing to reduce fuel consumption. Now it’s ‘How long can the battery last?’ That’s the big play. You’re heating the material to 920 to 940 C, and it’s just easier to form. But in the quenching process, there are some challenges as well.
Galling on the tooling is definitely a challenge. You’re quenching in such a rapid time. That’s very rough on the tooling. And material handling…automation’s come a long way, but still, to handle a part that’s 940 C…when you put the blank into the press to form the part, it’s so hot, it looks like an orange towel. Tooling and handling, those are some of the challenges.
Simulations have come a long way, so those challenges are becoming less and less. There’s a lot of R&D going on and has been for quite a while now, so there are many technological advances.
4. What are some hot stamping advances?
Ausmann: There are process windows that must be set to ensure that you’re still safe within the zones of what you want to produce. You can work in a larger window for faster cycle times. The problem is, if you speed something up too much during the process, you can have other issues with the integrity of the part, especially important for the crash effect.
Also, new materials. While hot aluminum stamping has been around for a little bit, it’s gaining in popularity now with electric vehicles (EVs). You don’t have to heat aluminum as much, but then it has a secondary annealing process, so it’s a longer process. Aluminum has its advantages and disadvantages. So, designers of the vehicle have another tool in their toolboxes.
Other material advances are layered materials with different thicknesses so that you don’t always have to have a thick, heavy part in the vehicle. You can optimize what the most economical part is with simulation and finite-element analysis.
Manufacturers are developing some hybrid approaches where they’re stamping the part in its martensitic state and then doing some additional forming, or different approaches to the quenching. A lot of OEMs currently use zoned hot stamping, where certain zones are purposely not hardened—they don’t want it fully hard or brittle in some areas—so a softer area helps the vehicle’s crash performance. You can do it in the tooling. There actually is a separate furnace where they adjust the temperature of that area. There’s a transition zone from the soft to the hard area. It’s a slower process.
They may perform a combination of direct and indirect stamping, or forming the part cold and then run it through the furnace to add the final forming and quenching steps.
Tooling and dies have come a long way. The big difference between cold and hot stamping is that with hot stamping, you need a cooling/quenching mechanism. When hot stamping technology first came out, in the forming sections, the cavities were milled out; now they’re more likely to be gun-drilled, so the channels go through the tooling.
Sometimes if the part has a patch—an extra-thick section of material in an area where you need the extra support—that area might need additional cooling. You might need a cooling cavity in that area to absorb a lot more of the heat, to balance it and to increase the efficiency for a shorter cycle time.
5. What are some furnace and roller improvements?
Ausmann: The biggest difference is that you either have a chamber-type furnace—some people call it a pizza oven—with different layers; you actually can open each door separately. Or there is a longer, roller-hearth furnace that enables the part to slowly get up to speed and just go through the furnace continuously. OEMs prefer one over the other, but roller-hearth furnaces are most popular.
The rollers have come a long way, too. For example, one of the furnace companies has a cactus design. It’s a unique form; it has less contact, so less of the coating is on the material as it goes through the furnace that can contaminate the rolls. So, you have less maintenance, less cleaning, and less overall cost and downtime.
Most materials for hot stamping—95%—are coated, so rollers with this cactus design make it a lot easier to prevent galling. That brings some other challenges. Controlling atmospheres in furnaces is very important. During the process, you don’t want to disrupt the coating, so the tooling must be modified at times to ensure that the coating remains intact.
6. How has simulation software evolved to improve hot stamping?
Ausmann: Simulation has helped advance hot stamping. Years ago, we used three different simulation-software companies. We had to make our own cards for hot stamping. So, we’d take coils of material and do testing against the grain, with the grain, 45 deg. to the grain. …Some OEMs insisted that they show you the grain direction, but the grain actually becomes uniform after the material is hot stamped. We’d then compare the simulations and approaches from the three different software companies to get best practices … go back to the actual tool—whether it was the prototype tool or the production tool—and feed that back to the simulation and fine-tune the program.
Simulation software has come a long way, with suppliers looking at friction analysis, the heating and cooling, and all that put together is a pretty complex recipe.
Simulation software saves a lot of time upfront. In the past a designer maybe was not as confident with the manufacturability, especially in the steel making. Now designers have support from the simulation. Usually the tooling or production companies give feedback as well, so they can design a part that’s feasible to make. It’s amazing how close the first hits are.
7. Have you seen changes in the presses?
Ausmann: Ultimately, the press goes up and down. Hot stamping usually uses a hydraulic press, although servo presses have shown a lot of advantages for hot stamping, to control the speeds and the press curves. With hot stamping, you need to hold the press on bottom so that you can quench the material. That’s really where the magic happens. Some parts require a very rapid closing, so you need to adjust the speeds. For part exit, you want to increase the ram speed moving upward so that the part comes out as quickly as possible. A lot of Industry 4.0 has been added to the controls of the press, so it has its own recipe for each part.
8. How has post-processing progressed?
Ausmann: In the past, post-processing included hard trimming the edges, but that was very difficult for the presses. Tooling wear was very high. Trimming was a very expensive process.
Over the years, laser cutting technology has developed for trimming hot-stamped parts. Some manufacturers feed the hot-stamped part directly into the laser for trimming, then direct feed into the subassemblies, and in some cases even direct feed into the final assembly. That process reduces floorspace and inventory…that’s a big improvement.
9. Do you see the use of hot stamping technology growing?
Ausmann: Definitely, hot stamping is a growing market, as we have seen at this conference. The percentage of vehicle content has really taken off. EV technology is pushing carmakers to come out with products that are lighter, safer and more manufacturable. It’s really taken off since it started in Sweden a few decades ago.
Other mass transportation industries now are looking at hot stamping—railways, trucking, aerospace, even bicycles. The more companies that get into hot stamping, the less investment it will take. As it becomes more of a commodity in the future, rather than specialized, we’ll see that the piece price that OEMs pay for hot-stamped parts will come down.
10. When Tesla developed its gigacasting, replacing as many as 70 stamped parts, many stampers were alarmed at the prospect of losing stamping business to castings. Now that Tesla has been able to hot stamp a very large part that formerly had been a stamped assembly, does this signal a return to stamping technology?
Ausmann: With gigacasting, Tesla really shook the market. It made everybody wonder what direction they should go in, in terms of the assembly and making assembly easier with fewer parts. It definitely makes production easier. If the volumes are there, that helps, of course. But a lot of suppliers are taking on the challenge with hot stamping as well, so that’s great to see. MF
To be considered deep drawn, the height of the case is usually at least two times the diameter. Deep drawn cases are used to enclose technology, especially in demanding environments or whenever tight tolerances and reliability are important.
The deep draw process starts when a flat piece of metal, called a blank or disc, is placed over a cavity called a die. A punch then forces the metal through the die, forming it into a shape.
These precision punches and dies are known as tooling. The tooling is set up in power presses which produce the tonnage, or energy, needed to force the material through the draw process.
During the draw process the material moves into the shape of the die. The flow of material is controlled through pressure applied to the blank and lubrication applied to the die or the blank.
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Each draw operation is a separate step and each step reduces the diameter and increases the height of the part. It may take five or more draws, also called reductions, to achieve the final shape.
Many factors, including material type and thickness, corner and bottom radii, and shape, determine the number of reductions required to make an enclosure.
More information about deep drawn stamping.
Deep draw, or deep drawing, is a manufacturing process commonly used for forming sheet metal into 3D shapes. The term “deep draw” refers to the ratio of the objects created from this process, which are often deeper than they are wide. Deep draw processes can be used to form a variety of shapes, including rectangles, cylinders, or spheres, often referred to as “cases.” These metal cases can be used for applications such as conventional housewares such as pots and pans, as well as battery enclosures, automobile gas tanks, and medical device components.
Learn more about the deep draw manufacturing process.
A wide variety of metals can be used in the deep draw manufacturing process, including stainless steel, aluminum, nickel, and titanium. Metal alloys, such as iconel and hastelloy, are made from a combination of base metals and can provide unique combinations of heat resistance, formability, and strength-to-weight ratios.
There are certain characteristics that allow particular metals to be drawable. The key indicators are the tensile strength, yield strength and elongation – how much will it stretch or bend before it tears. Hudson Technologies has developed the ability to draw Aluminum, Brass, Copper, Cold Rolled Steel, Stainless Steel, Nickel Silver, MU-metal and Cupro Nickel alloys, with specialized talent to draw Titanium, Inconel, Hastelloy, Nickel and other alloys.
Learn more about materials used in deep draw metal manufacturing.
Many factors influence success or failure when considering a deep drawn case as an enclosure solution.
Deep drawn components can offer significant material cost saving over machined parts. While turned parts often retain less than 50% of the originating stock, the deep drawn process typically retains closer to 85%.
When exploring non-round shapes such as squares and rectangles, the inside corner and bottom radii are two of the most important factors to consider. Generally, there is a relationship between the desired material thickness and the requested corner radii.
The general rule is the material thickness times two, equals the smallest corner radius obtainable (larger corner radii are desirable and may reduce the amount of draws). Exceptions can be made with additional draw operations to further reduce the corner radii. Caution statement – increased material thinning and adjacent sidewall bow can occur in some cases.
Draft or taper are inherent to drawn cases. A small amount of draft is necessary in order for the case to strip off of the punch after the draw operation. This will render the can slightly smaller on the closed end inside and larger on the open end inside. Our standard draft is .001″ (.025mm) per inch of length.
Drawn cases also tend to have different material thicknesses throughout their length. The bottom of the can (closed end) is generally thicker than the sidewalls. Some materials have a tendency to thin or stretch more than others.
In some cases, depending on the particular requirements, the tooling may be designed to intentionally thin or “iron” the sidewalls beyond the natural tendency. This may add more dimensional stability and a produce a more aesthetically pleasing case.
Burrs occur whenever metal is cut, trimmed or pierced. A burr can be discussed as displaced, attached material beyond the flat plane that is perpendicular to that surface.
This is a result of the shearing and subsequent break of the material during the cutting/piercing process. Burr height and direction can be controlled with tooling clearances and punching direction. Our standard burr height is 10% of the pierced material thickness unless otherwise requested. Burrs can be removed through additional mechanical or chemical processes.
Work hardening, or cold working of material during the deep draw process, must be relaxed through a heat treating process known as annealing. This process occurs as an intermediate step during the forming and case reduction sequence.
Annealing is a specific temperature and atmospheric environment designed to relieve stress created from cold working. Each metal type has a unique recipe of time, temperature, atmosphere, and cool down rate.
Atmosphere refers to the gaseous environment used in a vacuum or forced flow furnace. Common atmospheres are Hydrogen, Nitrogen and Argon. Selected gases generally prevent oxidation of the parts and provide an intergranular cleansing.
Due to the criticality of the annealing process, Hudson Technologies heat treats its parts in-house when applicable.
Yes. Many customers save time, reduce costs and consolidate their supply chain by having parts supplied with holes, slots, notches, tapped holes, inserts and screws. Brackets can be pressed, welded or brazed in place.
Modifications can be performed using hard tooling or milling, and drilling equipment.
Considerations should be made with respect to hole placement for screw and insert head clearance, proximity to a wall or radius and wall material thickness for an adequate number of tapped threads.
Hudson Technologies can also provide cases with paint, powder coated, silk-screened graphics and various plating types.
All we need is a drawing or sketch with dimensions and tolerances and we can quote the appropriate tooling or process.
More details can be found in Core Capabilities and Deep Drawn Stamping.
DFARS (Defense Federal Acquisition Regulations Supplement) is a reaffirmation of the Berry Amendment that mandates certain products that are manufactured for the US government and its suppliers who must have raw materials and/or processes provided from approved sources or countries.
This is important information to provide when requesting a quote to ensure that our raw material source choices are compliant to this requirement.
RoHS (Reduction of use of Hazardous waste Substances), is a European directive
that limits or eliminates the use of certain hazardous materials in the manufacture of electrical and electronic products.
Some raw materials and plating types fall under restriction of use to this directive. This is important information to provide when requesting a quote so that the proper research is performed and alternatives can be offered to remain compliant.
REACH is a European Community Regulation on chemicals and their safe use (EC /). It deals with the Registration, Evaluation, Authorisation and Restriction of Chemical substances. The new law entered into force on 1 June . Hudson Technologies‘ products are REACH compliant.
Cosmetics: The nature of the deep draw process can leave minor cosmetic imperfections on the cases. Minor scratches on the inside and outside that show no measurable material displacement would be considered acceptable.
Small surface dings or tool repair marks, including raw material flaws would be a reasonable expectation. Slight scuffing, burnishing and surface appearance changes on any given surface are considered normal conditions.
Cleaning Process: Every effort is made to remove the manufacturing lubricants and processing contamination. Cleanliness would be described as free from residual oils, particles, and tack free. Surface staining or minor discoloration from rinse cycles including water deposits are normal.
Cold Rolled Steel: Plain steel parts tend to rust quickly after fabrication. All efforts are made to reduce rust including intermediate application of rust preventing solutions. A slight brown/red discoloration of the material is considered normal. We will not ship rust pitted parts.
If any of the above conditions are not acceptable to your process or requirements we can, upon request, develop the manufacturing and handling process to ensure compliance to the request. Hudson Technologies can provide a quote for this service.
According to recent news reports, Kobe Steel allegedly falsified raw material tests certifying the production specifications of their aluminum and copper products from September through August .
Hudson Technologies has not purchased any raw material from Kobe Steel, either directly or indirectly from other raw material processors that show Kobe Steel as the originating mill. We have extensive traceability for all raw material used to manufacture our products, including the disclosure of the originating mill.
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