Notable

 

Developing Lightweight Bimetal Structures with Linear Friction Welding

Linear friction welding is not new. According to The Welding Institute (twi-global.com) of the U.K., they pioneered the process that’s predicated on one component being oscillated at high speed against the surface of a stationary component such that plasticization occurs and the two pieces are bonded more than 30 years ago.

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But whereas friction welding has had extensive use in the aerospace industry for making things like blisk assemblies for aircraft engines, it is now drawing greater attention in automotive.

A key reason? It permits the joining with a forged-quality weld of dissimilar materials.

Case in point: Manufacturing Technology Inc. (MTI; mtiwelding.com) has delivered a linear friction welding system to the Detroit facility of Lightweight Innovations for Tomorrow (LIFT; lift.technology). According to MTI, the LF35-75 has a footprint of 22 × 14 ft. The machine is designated LF35-75 because it can provide 35 tons of oscillator process force and 75 tons of friction force.

The process is also at least twice as fast as traditional welding, with the entire joining cycle completed in a few seconds. No consumables are required, nor are flux, filler material or shielding gases. And while it can take a good amount of energy to grip, scrub and squeeze masses of metal against each other, the process nonetheless uses about 20 percent less energy than that used by traditional welding methods, according to MTI.

LIFT is a public/private partnership set up by University of Michigan, Ohio State University, and the Edison Welding Institute (EWI; ewi.org) to research lightweighting for the transportation industries.

Applications currently being investigated include structural components such as chassis and doors, and energy absorption components such as crash cans, wherein a tubular structure is joined to a plate structure.

MTI and LIFT have an agreement to share use of the machine. MTI will run and maintain it at LIFT’s Detroit facility in support of LIFT’s research as well as use it to demonstrate parts for its own customers.

 

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The LF35-75 linear friction welder on its way to LIFT in Detroit.

Source: MTI


 

Lasers Provide Flexibility for Blanking

The challenge of flexibility is something that suppliers of stampings have long grappled with—for a given sheet metal blank there is a given blanking die, and when the vehicle design changes, the blanking die must be changed as well. Almost the definition of “inflexible.”

SET Enterprises (setenterprises.com), a supplier of blanks, has found a solution: a high-speed blanking line that uses lasers in place of hard tools.

This means that when the part configuration changes, it is simply a matter of changing the program in the controller. No dies are required.

The laser blanking line was developed by Schuler (schulergroup.com).

The three laser heads, which have a combined output of 12 kW, have a straight-line cutting speed of 100 m/min from a coil that’s unspooling at up to 60 m/min, so this means it can readily meet production volume requirements.

The heads can cut contours of all configurations, and parts can be nested, as well.

SET is installing the system in its facility in Chicago; it is scheduled to go into production Spring 2019.

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Blanking line uses lasers rather than dies for cutting. Saves material and offers high flexibility.


 


A Counterintuitive Approach to Printing Metal Parts

Hybrid additive/subtractive systems for printing and finishing metal parts have been around for years now. With these systems, a part is completely printed and then is brought to necessary tolerances (i.e., edges, details, surface finish) through machining. It’s always been “first build it, then cut and polish it.”

A process developed by 3DEO Inc. (3deo.co) uses a radically different hybrid method.

3DEO’s process makes metal 3D printed production parts to spec in a counterintuitive way. The company’s Intelligent Layering system, like other liquid binder systems, applies a binder to a bed of metal powder to build a part that will eventually be sintered in a furnace. While some systems apply the binder only where it is needed to build up the part, Intelligent Layering instead goes wide: the binder is applied uniformly over the entire powder bed.

This isn’t even low-resolution—it’s no-resolution.

Then, micro CNC mills that are part of the 3DEO system deploy to precisely cut the outline and interior cavities. Another thin layer of powder is applied, followed by the binder spray, and the mills come out again.

In the fight to get as close as possible to net shape prior to CNC machining, 3DEO goes straight to CNC machining from the start.

To reach the best tolerances, the part can be cut a layer at a time. But up to ten layers can be built up before cutting, which saves time and also enables 2.5-D features to be included. The machine can also cut at depths of less than a full layer’s thickness to create intralayer features and enable finer tolerances than the printer could unaided.

The result is a “green” part that needs to be sintered in a furnace after loose powder is removed. Furnace-sintered parts lose some volume, but it’s a well-understood process and can be compensated for at the outset. The sintered parts come out of the furnace with a density of over 99 percent and with a finish of about 100µin. Ra. They meet the MPIF Standard 35 for quality. The current system has an 8 × 8i-n. build area and can print 17-4PH and MIM 316L stainless steel, with more types of metal to follow.

The system offers cost-savings benefits, like using standard metal injection molding (MIM) powders. Another cost-saver: cutting unsintered bound metal powder is a lot easier on a cutting tool edge than cutting solid metal, so much so that, after cutting over 10,000 parts (on three different machines), the company says it has not yet had to replace a cutting tool.

3DEO isn’t selling the system itself—or at least not yet. Rather, it’s a service provider, using the system to print parts for customers on demand.

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Diagram of the 3DEO hybrid system. (Source: 3DEO Inc.)


 

Smart Sensing for Robotic Applications.

This, of course, is an end effector, the business portion of a robot’s arm, in this case with grippers on the very end. But what’s worth noting about it is that portion in the middle, the piece with the ATI label on it. That is a force/torque sensor, the Axia80, which is capable of measuring all six components of force and torque, and which then communicates back to the controller via EtherCAT or Ethernet, thereby improving assembly, grinding and polishing applications. The transducer includes silicon strain gauges that not only reduce noise but provide overload protection from five to 20 times over the sensing range. The sensor, from ATI Industrial Automation (ati-ia.com), can be programmed with two different calibrations: one for a large sensing range for high-speed or high-force operations and the other for those requiring higher resolution and accuracy; the operator can switch between the two while the operation is running.