Material advances: Higher strengths, lower weights for demanding applications

Smaller, lighter, cheaper.

Whether you’re making parts for surgical equipment, emissions systems for 18-wheel trucks, or seats on airplanes, reducing size, weight, and cost are competitive issues for manufacturers. As tolerances shrink and duty cycles get more demanding, advanced materials companies are developing new metal-working technologies, composites, and manufacturing techniques to meet next-generation challenges.

Steel producers have found ways to improve strength, allowing manufacturers to use less metal without sacrificing structural integrity. Aluminum producers are exploring technologies to improve formability and lower costs. And polymer and composites companies are developing higher-strength, lower-weight materials that can be extruded faster than in the past.

In this special report, explore how new equipment is helping a plastics company speed testing and development of new materials, how combined polymer materials are impacting medical device and automotive component design, how companies should evaluate materials for 3D-printing applications, innovative uses of advanced powdered metals, and how polymer parts are impacting motorsports.
 

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Custom thermoplastic elastomer test systems

Advanced controls from Siemens on KraussMaffei Berstoff extruder test systems speed time to market for thermoplastics producer Kraiburg TPE.

Kraiburg TPE Corp. in Duluth, Georgia, is a manufacturer of custom thermoplastic elastomer (TPE) compounds for the automotive, medical, general industrial, and consumer sectors.

Its product development department routinely evaluates material batches and new custom compounds for performance and customer specification viability. Integral to that process, Kraiburg TPE engineers use sophisticated co-rotating, twin-screw extruder technology from KraussMaffei Berstorff in Florence, Kentucky.

Owing to varieties of hardness, color, and performance properties required at Kraiburg TPE, monitoring every aspect of the machine performance is critical. This includes all temperatures, speeds, pressures, and torque on the extruder, plus a gear pump, underwater pelletizer, and multiple loss-of-weight feeders used on the line.

“The lab extrusion line is used for both process and product development assessment,” says David Frankenberg, senior application engineer at KraussMaffei Berstorff, describing a machine installed at Kraiburg TPE. “A key requirement was the generation of all data in real time, as part of the management system to be used, as well as the condition-monitoring system needed for predictive maintenance strategies.”

Engineers at Kraiburg TPE and KraussMaffei evaluated several control schemes before turning to Siemens for assistance.

Data-rich controls
As Frankenberg and electrical engineering associate Martin Gonzalez detail, the Siemens EXT3370 application package blends the current programmable logic control (PLC) technology and drives platform with a human-machine interface (HMI) capable of providing all graphics and multiple data screens on a single display. In addition, the system had the ability to feed the big data directly to the Kraiburg TPE process data archival and analysis system, where it would reside for real-time and long-range performance evaluation by the product development, quality, and process teams.

All speeds, pressures, temperatures and other parameters can be instantly assessed, using set point and actual value data on the display, either at the machine HMI or a remote monitor within the Kraiburg TPE network.

On the KraussMaffei Berstorff machine, the control system comprises the software solution, Siemens drives and motors, the ability to monitor up to 32 temperature zones, touch screen technology on a 15" HMI, and scalability on the drives to accept the ancillary equipment being monitored at the Kraiburg TPE facility. In this way, a customized solution was devised using a standard, cost-effective array of components, Frankenberg says. He notes the training needed was minimal, owing to the plain language on the control with no need for knowledge of high-level programming skills. All compound recipes can be transferred via USB for portability and security.

Allen Donn, product development engineer at Kraiburg TPE, along with his team of engineers and tech specialists, evaluated installation and commissioning of the machine at the Duluth facility.

“The data transfer from the PLC into the same process data archival and analysis system that we use for our other lines at Kraiburg TPE. A simple Excel file is generated with any parameters desired for analysis, plus we can easily exchange data between R&D and production here. The result is that our ability to utilize production machinery more efficiently has increased substantially with the use of the new KraussMaffei Berstorff machine in our test department, as the control system gives us real-time hard data we can use to make adjustments on new recipes and entirely new materials.”

Kraiburg TPE performs extensive new compound property performance testing on its TPE formulae and the time compression realized by using the extruder line in this real-world R&D operation is providing substantial advantages.

Machine improvements
Kraiburg TPE typically runs materials in the 20 Shore A to 80 Shore A hardness range and, as an example, might test a variety of adhesion grades for over-molding onto polycarbonate, nylon, or other substrates, Donn explains.

“When we can pull the data from any machine in the system, adjust it, run it on the R&D machine, and then feed that data back into production, it makes a huge difference in our efficiencies,” Donn says.

In one instance, shortly after the KraussMaffei machine was installed, Kraiburg TPE engineers were testing 15 compound varieties on the machine very quickly, compared to using production equipment to do that task.

“I could look into the software to compare all set point and actual values, remotely, over the entire test period,” Donn notes. He adds that the substantial raw material cost savings of more tests, faster results, and less waste all contribute to an improved profitability for the company.
 

Kraiburg TPE Corp.
www.KRAIBURG-tpe.com

KraussMaffei Group USA
www.kraussmaffei.com

Siemens Digital Factory
www.usa.siemens.com/plastics

 

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Innovations in powdered metals

The Metal Powder Industries Federation recognizes creative materials applications.

Announced at the Metal Powder Industries Federation’s POWDERMET2015 International conference on Powder Metallurgy & Particulate Materials, the 2015 Powder Metallurgy Design Excellence Competition recognize manufacturers for innovations featuring precision, performance, complexity, economy, innovation, and sustainability. Profiled here are several of the winning automotive parts that show advantages of powdered-metal design flexibility.

Steering rake cam

Keystone Powdered Metal Co.
Grand Prize Automotive:
Chassis Category

Rake cams, right-hand and left-hand guides, and an eccentric cam made for customer Nexteer Automotive, are diffusion-alloyed steel components used in Cadillac ATS and CTS, Chevrolet Impala, and GM Holden Commodore (Australia) steering columns. A key element of tilt and telescope adjustment features, they maintain position during a crash.

The multi-level parts are fabricated to net shape with inline heat treatment and tempering being the only secondary operations preformed. Features allow for a mechanical lock of the plastic over-mold, in an operation performed by Agapé Plastics Inc. The customer’s preferred design for the tilt/telescope adjustment and lock – with a pin pocket that gives a positive detent feel – could be met only with powder metallurgy.

 

Transmission washers

FMS Corp.
Grand Prize Automotive:
Transmission Category

A thrust washer and two back-up washers help Allison Transmission’s TC10 automatic transmission cut fuel use by 5% in Class 8 commercial trucks, lowering CO₂ emissions.

Using a proprietary low-alloy steel, parts are warm compacted to achieve high green density, then vacuum sintered at high temperature, gas-pressure quenched, and tempered. Produced very close to net shape, the washers’ original powder metallurgy designs are estimated to save 30% compared to the cost of forged/machined components.

 

Stainless steel flange

SMC Powder Metallurgy Inc.
Award of Distinction Automotive:
Engine Category

A stainless steel flange made for Kendrion FAS Controls connects and seals a spill valve in an automotive direct-injection fuel system. Replacing a heavily machined wrought part, the flange is made from a proprietary premix developed for dimensional stability. The part requires perpendicularity relating to the machined counterbores and O-ring groove.

After compaction, parts are de-lubed, placed on slates for high-temperature sintering in 100% hydrogen, and resin impregnated.

The customer believes this is the only PM part used in a high-pressure fuel system. More than 1.6 million flanges have been shipped.

 

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Materials for wearable medical devices

Combining polyester and polycarbonate increases stiffness and strength and resists cracking, making the combined material well suited for durable, wearable devices.

Medical technology continues to advance at an accelerated pace. Helping patients be comfortable and mobile while monitoring vital signs, managing short-term health issues, or even chronic conditions is one area of focus. Increasingly, wearable medical devices are aiding this need. Though wearables are popular for health-conscious consumers, this area is also attractive to healthcare providers and doctors since they can gather real-time patient data and offer the promise of truly tailoring therapy to the patient.

IndustryARC research estimates the global medical wearable electronics market was worth more than $2.8 billion in revenue in 2014, a figure that is expected to exceed $9 billion by 2020. Heart rate monitors and blood glucose level monitors are the fastest-growing devices among all device types (http://goo.gl/rHWZuY).

Technological innovations are key enablers. Along with improvements to the medical technology, materials innovations are playing a role in making the design and manufacture of increasingly sophisticated wearable devices possible. Manufacturers are creating new designs that streamline the shape of wearable medical devices to further improve patient experiences.

New designs = new material challenges
Wearables can be particularly useful for patients with chronic conditions. In addition to wanting wearables that fulfill their medical purpose, patients want small, lightweight, and comfortable devices. New designs make the wearable devices less obtrusive. In addition to making the wearer more comfortable, streamlining and modernizing designs could have a positive psychological effect by reducing the stigma sometimes associated with wearing such devices. But altering the design to allow for thinner, flatter, or curved devices can have implications for the housing materials.

New materials developed to meet the requirements of wearable medical devices include the Makroblend M525 polycarbonate/polyester blend from Bayer MaterialScience LLC, which combines the superior properties of the polymers. The polymer’s dual nature as both amorphous and semi-crystalline means it can retain some of the best attributes of both. The amorphous nature enables it to bond well with adhesives and welding techniques, unlike semi-crystalline materials. The crystalline nature enhances chemical resistance and improves flow during molding.

Makroblend application In addition to wearable medical devices, Bayer’s combination of polycarbonate and polyester has been used widely in electronic and automotive applications. The Audi A7 sedan features a Makroblend spoiler that is composed of two components: a structural part and cover that are glued together. For the structural part, Audi’s design team sought a material with strength, UV protection, and chemical resistance to gasoline and cleaning agents. The cover required a paintable, high-quality, Class A surface with uniform surface quality to match adjacent metal parts, and a low-gap design. Bayer developed Makroblend UT235 M, 15% mineral-filled grade to offer a low coefficient of linear thermal expansion (CLTE), high heat resistance, improved flow, and a Class A surface.

Supporting over-molding
Those rugged characteristics are key because wearable device designs are adding smaller numbers of more-complex components. As devices shrink, original equipment manufacturers (OEMs) want to reduce the number of components that must be molded then assembled to produce the finished device. They also are looking for opportunities to create a water-tight seal, so that the wearer can use the device in a variety of weather conditions and while participating in water-based recreational activities. For these reasons, they are increasingly turning to over-molding.

Over-molding, the process of molding around inserts, facilitates compact designs with molded-in, watertight features, such as windows and battery tubes. New materials have been developed to address the unique requirements of these designs. The over-molding process tends to mold in elevated levels of stress due to constrained shrinkage. Many plastics can stress-crack over time or exhibit reduced resistance to chemical agents. Makroblend M525 has been formulated to resist this behavior. Specifically, it has demonstrated cracking resistance and maintains resistance to the skin care products normally encountered by wearable devices.

The low shrink rate of this polymer blend means that Makroblend M525 can be molded to tighter tolerances and will demonstrate less dimensional variability.

Thin, stiff materials
The flexural modulus, or stiffness, of this material is very high for an unreinforced plastic. As such, it does not need to be as thick to provide the same level of stiffness or support. This can allow for slimmer designs, which can be important for wearable devices.

Since stiffness is provided without impact-reducing additives such as glass fibers or mineral fillers, the polycarbonate/polyester blend delivers an unusual balance of stiffness and toughness. This combination is important in devices that contain delicate components such as screens, electronics, sensors, and other components that need to be protected from impact or crushing.

The relatively high modulus of Makroblend M525 helps it to resist creep and stress relaxation, which can cause lower modulus materials to change shape or lose tightness-of-fit. Parts molded from this material should maintain good dimensional and structural integrity through a greater range of environmental conditions.

This new material also meets the testing requirements of ISO 10993-5 (cytotoxicity) and ISO 10993-10 (irritation and sensitization) for biocompatibility.

Next-generation wearables
From monitoring vital signs to delivering drugs, wearable devices perform a variety of tasks. As technology evolves, wearable medical devices are expected to facilitate continuous, more integrated health monitoring and drug delivery. Medical and patient communities are embracing the move toward less invasive yet more convenient and sophisticated wearable medical devices. Materials suppliers will work closely with OEMs, tailoring their materials to evolving requirements, helping to help bring this next-generation of devices to market.

Bayer MaterialScience LLC
www.materialscience.bayer.com

 

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Thermoplastic materials for additive manufacturing

3D-printing compatibility and toxicity compliance

Is there a hotter manufacturing topic in any industry today than 3D printing? Additive manufacturing is capturing intense interest because of its advantages, one of which is rapid prototyping.

SABIC recently employed the technology to create a prototype of a sleek, ergonomically advanced, economy class aircraft seat, using a design by Italian design firm Studio Gavari. The seat was created to inspire seating tier-suppliers to take a fresh look at seat design and consider new ways of manufacturing various seating components, if not the entire seat.

To take the seat a step further into the feasible, this proof-of-concept design was fabricated using filaments made of SABIC’s Ultem 9085 resin. An advanced thermoplastic material, it is compatible with 3D printing as well as being FAR 25.853 and OEM toxicity compliant. The material is often chosen for a wide range of aircraft interior applications because it offers low moisture absorption, design flexibility, and versatility.

As a resin, it can be injection molded; as a sheet, it can be used in thermoforming; and it can also take the form of a non-woven material for fire blockers and acoustical panels. Using 3D printing enabled the rapid prototyping of the design, resulting in a seat with fewer than 15 components, compared with the typical seat’s 200 parts.

Technology adoption
But what will be required for this evolving technology to fully benefit the aerospace industry? The adoption of additive manufacturing across all industries continues to increase as technologies evolve and improve in speed, part performance, and aesthetics. However, for additive manufacturing to reach its full potential as a manufacturing process for aerospace customers, we believe the industry will require:

• A process that is able to produce thermoplastic parts approaching the performance of injection molding. This will require materials designed specifically for 3D printing
• A broader range of material availability, including materials with the same properties and features that are available today with other technologies, such as flame retardant, UV stabilized, etc.
• An economic build opportunity – reduced material costs, increased print speeds, and reduced secondary operations

Perhaps most importantly, tier suppliers will need to become more proficient at designing for additive manufacturing by leveraging topology optimization and extreme part consolidation techniques in order to realize the full value this technology can offer.

 

As a case in point, recently, SABIC worked on a project for the lighting industry – searching for innovation and efficiencies in luminaire design and production. Using predictive engineering and 3D printing technology, engineers created an integrated thermoplastic LED luminaire which highlighted the opportunity to reduce parts by 84%, weight by 24%, and assembly time by 65% compared to a conventional metal luminaire. This was a great opportunity to help customers understand how using additive manufacturing technology can quickly turn an insight into a real cost-competitive solution. SABIC’s global application development centers are expanding their focus on additive manufacturing technologies including fused deposition modeling (FDM), selective laser sintering (SLS), and big area additive manufacturing (BAAM).

The company continues to expand its portfolio of 3D printing solutions – materials, design optimization, and processing techniques – to help customers achieve improved part performance, enable design freedom, enhance part aesthetics, and provide more economical part yields.
 

SABIC
www.sabic-ip.com

About the author: Kim Choate, market director, mass transportation, Innovative Plastics SABIC, can be reached at media.inquiries@sabic-ip.com.

 

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Polymer motorsports components

Saint-Gobain Seals’ material replaces sintered-metal parts in high-performance racing applications.

Edited by Arielle Campanalie

Used in Formula One race cars and MotoGP motorcycles, gerotors (combined generators and rotors) are positive displacement pumping units consisting of two elements: an inner rotor and an outer rotor. The outer rotor has an additional tooth compared to the inner rotor and its central axis is positioned at a fixed eccentricity from the one of the inner rotor and the shaft. Rotation of the two elements, one against the other, allows the fluid to be pumped in a smooth movement. Typical working conditions include temperature level of around 150°C, pressure at only a few bar, with speeds of 20,000rpm.

Metals are traditionally used to manufacture gerotor elements, either sintered metals, stainless steel, or aluminum. Saint-Gobain Seals developed and tested its Meldin 5330 material – a filled PEEK compound – for gerotors for about a year, collaborating with a customer seeking weight saving and long wear. The polymer was suitable because of its mechanical properties at high temperature and balance between being wear resistant and compatible with the aluminum counter surface.

Additional advantages include minimal chemical absorption and deformation as well as low coefficient of thermal expansion. The polymer material minimizes the wear of the gerotor material, improving sealing and pump efficiency.
 

Saint-Gobain Seals
www.seals.saint-gobain.com