Springs + Rings + Seals - Motion Control Tips

What are rotary unions and how are they used in motion applications?

September 25, 2018 By Danielle Collins Leave a Comment

Rotating components are common in motion applications — robot arms, winders, spools, spindles, and rotary tables are just a few examples. And while creating rotary motion is easy, when air or liquids need to be transferred from a stationary supply to a rotating component for cooling, heating, lubricating, or transmitting fluid power, the task becomes more complicated. This is where rotary unions come in.

Rotary unions provide an interface that allows fluid media — air, steam, or liquid — to be transferred between a rotating component and a static component. They’re designed to accommodate a wide variety of media conditions, including very high and low temperatures, flows, and pressures, including vacuum applications. And unlike other fluid transfer mechanisms, rotary unions work for applications involving any combination of rotation angles, including continuous rotation in one direction.

This rotary union can be used for supplying cooling from a stationary source directly to a machine tool spindle.
Image credit: Dublin Company

Rotary unions are referred to by a variety of names, including rotating unions, rotary joints, rotary swivels, and rotary couplings.

There are numerous designs and configurations for rotary unions — in fact, they’re often custom-designed for the application — but all rotary unions are made up of four basic parts: the housing, one or more bearings, the shaft, and one or more seals.

The housing is typically the stationary part and is connected to the media supply. The shaft is independent of the housing and rotates with the connected rotary equipment. Media can flow through the union radially or axially via ports in the housing. The rotating part is supported by radial bearings — typically one or more fully sealed deep groove ball bearings.

The most important component of the rotary union is arguably the sealing mechanism, which prevents or reduces leakage between the rotating and stationary components, and must do so with minimal friction and wear. Seal types range from simple lip seals to more complex spring-loaded mechanical seals that automatically adjust to minimize the pressure on the seal faces, reducing friction and wear.

Of course, the fluid transfer should ideally be leak-free, but in some applications, completely leak-free transfer is not possible. For these cases, the media is prevented from being released into the environment by a collection system that recovers the leaked media, protecting surrounding equipment and personnel.

This video from Dynamic Sealing Technologies Inc. demonstrates how rotary unions transfer fluid between rotating and stationary component, with examples of their use in various industries.

Whether choosing a standard, off-the-shelf rotary union or designing a custom product, the following factors should be considered:

type of media being transferred
speed of rotation
flow rate of media
pressure of media
temperature of media
allowable leakage

The type of media is especially important, since the housing, shaft, and seal materials must be compatible with the fluid flowing through the union. Fluid media can range from water to highly corrosive liquids and steam, and manufacturers address the challenges of each by offering a wide range of materials, not only for the housing and shaft, but also for the seals.

Although single- and dual-flow designs are most common, rotary unions can include multiple independent flow paths that allow different media to be transferred concurrently without mixing. It’s also common for slip rings or fiber optic rotary joints to be integrated with rotary unions, allowing the passage of both fluids and electrical or fiber optic cables.

This cross-section of a two-passage rotary union shows the two separate channels through which different media can pass without mixing.
Image credit: Kadant Inc.

In motion control systems, rotary unions can be found in robot joints, especially for transferring air or fluid to end-of-arm tooling. They’re also used for passing vacuum or air pressure through rotary air bearing stages, and for supplying coolant and lubrication to machine tool spindles.

Feature image credit: Moog

Common challenges that wave springs address

August 13, 2018 By Lisa Eitel Leave a Comment

Updated November 2018 || Springs are flexible mechanical components to store and release energy or apply and release forces on machine axes. Wave springs combine flat (non-coiled) bow springs (as their waves) with traditional compression-spring coil geometry. For the design’s compactness (as a high force-to-work height ratio) and other benefits, some motion systems have migrated from traditional helical or coil springs to flat-wire wave springs.

Design engineers typically work with manufacturers to customize wave springs to specific operating conditions by material, thickness, number of turns, and other geometric features. That helps address or avoid the following spring-installation challenges.

Wave springs outperform other springs under the application of normal (non-twisting) forces. Data courtesy P. Ravinder Reddy and V. Mukesh Reddy

Column buckling in springs occurs with long free lengths and spring ends that can’t evenly distribute load around the spring circumference. Buckling mainly depends on geometry and not spring material properties. Traditional springs tend to buckle when deflection (for a set free length) is excessive. Such buckling is preventable by keeping the design to below critical deflection and length values. The former is the ratio of deflection to spring free length; critical length is the ratio of that length to the spring diameter. One rule of thumb for avoiding buckling in traditional springs is to keep free length to less than quadruple the spring diameter — and load to less than the product of spring rate, length, and buckling factor.

Wave-spring buckling factors vary greatly, but the value is nearly always higher than those of other springs. That means they readily hold their centered cylindrical shape and often self-locate into assembly bores — even operating reliably in machined assembly features held to relatively loose tolerances.

Spring surge is a potential concern in assemblies with a compression spring having one free end. Depending on the motion input, such springs can exhibit resonance that’s large enough to cause temporary loss of contact with the assembly housing — and damage surrounding machine elements. That’s an issue of highest concern if the spring material provides little damping and the spring operates on an axis that must make fast reciprocating strokes. Well-chosen wave-spring geometry and material can help avoid issues of spring surge and resonance excitation.

Mean, cycling, and localized stresses on the spring each load cycle (and the load cycle itself) dictate when spring fatigue failure could occur. For any spring design, more turns make for a longer MTBF … while longer springs generally have shorter MTBF. But no matter the variation, wave springs fatigue more slowly and have longer MTBF than traditional springs.

Springs under normal operation exhibit no permanent spring-rate or dimensional changes — called relaxation or set. But deflection under full load with stresses exceeding the spring material’s yield strength will induce permanent deformation that compromises the spring ability to deliver full design force or energy. This is often a concern in designs that must operate in extremely hot ambient conditions. Wave-spring deflection is about 25% lower than that exhibited by traditional springs. Wave springs are also more resistant to relaxation for comparable diameters, free lengths, and turns. One caveat: In designs necessitating fewer turns and shorter free lengths, sometimes traditional compression springs outperform wave springs by exhibiting less deformation.

Any spring under a twisting moment load exhibits shear stress and stores strain energy. Wave springs exhibit less strain energy than traditional spring variations (and lower equivalent stress values) so better withstand such loading.

Shown here are wave-spring application examples. From top to bottom, these include clutches, automotive vehicle mirrors, rolling doors, airbag inflators, water sprinklers, general airbag assemblies, night-vision lenses, and bayonet connectors. Image courtesy Rotor Clip Company Inc.

Updated: Basics of compression springs for motion designs

July 25, 2018 By Lisa Eitel Leave a Comment

Engineers incorporate compression springs in motion designs that need linear compressive forces and mechanical energy storage — designs such as pneumatic cylinders and push-button controls, for example. The most conventional compression spring is a round metallic wire coiled into a helical form.

Photo courtesy Lee Spring

This compression spring has a barrel shape for lateral stability.

The most common compression spring, the straight metal coil spring, bends at the same diameter for its entire length, so has a cylindrical shape.

Cone-shaped metal compression springs are distinct in that diameter changes gradually from a large end to a small end; in other words, they bend at a tighter radius at one end. Cone-shaped springs generally go into applications that need low solid height (the total height when compressed) and higher resistance to surging. Whether cylindrical or cone shaped, helical compression springs often go over a rod or fit inside a hole that controls the spring’s movement.

Other configuration types include hourglass (concave), barrel (convex), and magazine (in which the wire coils into a rectangular helix).

This compression spring has reduced ends.

Most compression springs have squared and ground ends. Ground ends provide flat planes and stability under load travel. Squareness is a characteristic that influences how the axis force produced by the spring can be transferred to adjacent parts.

Although open ends may be suitable in some applications, closed ends afford a greater degree of squareness.

Squared and ground end compression springs are useful for applications that specify high-duty springs; unusually close tolerances on load or rate; minimized solid height; accurate seating and uniform bearing pressures; and minimized buckling.

This concave (hourglass-shaped) compression spring can stay centered, even in large-diameter bores.

The key physical dimensions and operating characteristics of these springs include their outside diameter (OD), inside diameter, wire diameter, free length, solid height, and spring rate or stiffness.

• Free length is the overall length of a spring in the unloaded position.

• Solid height is the length of a compression spring under sufficient load to bring all coils into contact with adjacent coils.

• Spring rate is the change in load per unit deflection in pounds per inch (lb/in.) or Newtons per millimeter (N/mm).

The dimensions, along with the load and deflection requirements, determine the mechanical stresses in the spring.

When the design loads a compression spring, the coiled wire is stressed in torsion and the stress is greatest at the wire surface.

As the spring is deflected, the load varies, causing a range of operating stress. Stress and stress range affect the life of the spring.

The higher the stress range, the lower the maximum stress must be to obtain comparable life. Relatively high stresses may be used when the stress range is low or if the spring is subjected to static loads only.

The stress at solid height must be low enough to avoid permanent damage because springs are often compressed solid during installation.

Wave spring basics video: Spring force, work height, materials, and installations

January 13, 2018 By Lisa Eitel Leave a Comment

Within mechanical designs, tension, compression, and torsion springs take numerous forms to store and release energy. A wave spring is a type of compression springs made of flat wire. They are called wave springs because they have multiple waves per turn. The flat wire, along with the multiple waves per turn, combine to create the same spring force at reduced work heights compared to round wire coil springs.

Recent technology innovations in manufacturing, have led to applications decreasing in size — so the need for more compact springs has grown. A wave spring’s reduced work height (compared to that of a traditional coil spring) lets engineers shrink the overall height of the spring cavity. This often translates to a smaller assembly and potential weight savings.

Wave springs are designed around a spring force and work height. These requirements are determined by the application. The spring can be configured to accommodate cycling or static operations. A valve is an example of a cycling application. The spring oscillates between two work heights to regulate the valve. A wave spring can also be used in a static application such as preloading a bearing. In the bearing example, the spring is compressed to a work height and remains at that height for the lifetime of the application. This reduces vibration and ultimately prolongs the life of the bearing.

A wave spring is available in an array of materials. The material is dictated by the application environment. When the spring is not exposed to corrosive elements, carbon steel is the standard material used.

Wave springs are available in a range of stainless steels if the spring is in a corrosive environment. For high temperatures environments, an exotic alloy wave spring may be required. Common exotic alloys include, Elgiloy, Hastiloy, and Inconel.

The versatility of the wave spring allows it to be used in a variety of industries — including oil and gas, automotive, medical, and aerospace. Wave springs are used across these industries because they can range in sizes from as small as 0.157 in. (or 4 mm) to 120 in. or 3,000 mm in diameter.

Because wave springs are produced from coiling, manufacturing a custom spring can be an economical solution. Often only a simple set up is required, available with no tooling, to produce a spring that meets unique application requirements.

Retaining rings basics video: Stamped, eared, e-clip, and constant section

January 13, 2018 By Lisa Eitel Leave a Comment

As with other joining hardware (such as cotter pins, screws, and bolts) retaining rings prevent mating components from excessive moving. In short, they create a removable shoulder preventing components from migrating out of proper position during operation. Retaining rings are thin, circular, metal components that can be either stamped from a sheet or coiled from wire.

Retaining ring terminology

Retaining rings are designed to fit into a machined groove either on the inside of a bore or on the outside of a shaft. These components reduce vibration, retain two parts of an assembly, and can withstand axial loading. They are used in assemblies as a cost-saving solution … to avoid machining a shoulder onto a mating component.

Retaining rings exist in many forms including, stamped, spiral or Spirolox, constant section, hoop, e-clip, beveled, and wave-ring forms.

Recognize stamped retaining rings by their ears

Stamped retaining rings are manufactured from sheet metal and feature twin lugs, sometimes called ears. These are the most cost-effective retaining rings when working with small diameters. However, the stamping process generates excess scrap causing them to be less cost effective when working with larger diameters. Stamped rings are installed with the help of a special tool — snap ring pliers. The pliers are inserted into the lugs to separate or compress the ends so the retaining ring can clear the shaft or bore. Stamped rings can replace cotter pins and other traditional fasteners in an array of applications.

Radial retaining rings — also called e-clips

Another version of stamped rings are e-clips. These rings are installed by pressing them radially onto a shaft groove. This can be a standard shaft or a stepped shaft. Similar to stamped rings, they become less cost effective as the required diameter increases in size. E-clips are used when it is preferable not to slide a ring along the axis of a shaft.

Spiral retaining rings — a cost-effective and reliable option

Retaining rings can also be made from coiled flat wire. These are called spiral rings or Spirolox rings. (Spiralox is a registered trademark of Smalley Steel Ring Co.) Because they are manufactured from wire, there is less scrap — making them more economical at larger diameters or when using stainless steel and exotic alloys. This process is economical when looking for a custom ring because there is no dedicated tooling (such as custom punch and die tooling).

Spiral retaining rings come in single-turn or multi-turn varieties. Multiple turn rings have higher thrust load capacity and feature a 360° retaining surface. The constant cross-section gives spiral retaining rings a lug-free design, making them suitable where available radial space is limited. Because they do not have lugs, snap-ring pliers aren’t needed for installation. Instead spiral rings are wound one turn at a time into a groove. To extract a spiral ring from a groove, there is a removal notch that creates a gap between the end of the ring and the mating component. A blunt object (such as a screwdriver) can be inserted to pry the ring free. A notch at the end of the wire can start unwinding out of the groove for removal. Often a spiral retaining ring will fit interchangeably in a stamped ring groove.

Spiral rings can also be designed to act as an internal and external ring at the same time. This is called an ID-OD lock and permanently fastens two mating components. We see here a Spirolox retaining-ring example from Smalley.

Hoopster constant-section rings

Currently there are two additional types of flat wire rings, hoop rings and constant section rings. Hoop rings feature a narrow radial cross-section and a larger axial cross-section. They are installed into shallow grooves which makes them suitable for thin walled applications. In contrast, a constant-section ring is similar to a traditional spiral ring but is made from wire with a thicker cross-section and square edges. Constant-section rings are used in heavy-duty applications. Traditionally, both hoop rings and constant-section rings are single-turn.

Retaining-ring materials

Retaining rings are available in a diverse range of materials. The material is dictated by the application environment. When the ring is not exposed to corrosive elements, carbon steel is the standard material used. Retaining rings are available in a range of stainless steels if the ring is destined for a corrosive environment. With high-temperatures environments, an exotic alloy may be required. These alloys include, Elgiloy, Hastiloy, and Inconel. Retaining rings can also undergo different types of plating or receive different coatings to withstand harsh environments. Common finishes include, black oxide, cadmium plating, oil dip, passivation, zinc phosphate, vapor degrease (cleaning), and vibrator or hand deburr.

Custom retaining rings

Retaining rings can be customized to application requirements. Traditionally, rings produced from coiling are easier to customize. Often only a simple setup is required (with no tooling) to produce a specific ring. If the application requires a specific end type or configuration, this is easier to produce from a coiled ring than from a stamped ring. Custom rings can be manufactured in sizes from 0.157 in. (or 4 mm) to 120 in. or 3,000 mm in diameter. A custom stamped ring would require and additional set up and die.

What limits wave-spring working height and axial force?

August 15, 2017 By Lisa Eitel Leave a Comment

Wave springs are core to myriad gear, actuator, clutch, and consumer-grade motion assemblies. They are load bearing — included in designs to address play or compensate for dimensional variations. Wave springs apply load in axially — so are specified by working height (and other parameters).

Even at various work heights, wave springs apply consistent loads to within tight tolerances. That lets OEMs specify wave springs to very specific application requirements. Note how wave springs require less space than coil springs.

All springs are either for applying load in tension, compression, or torsion. Tension springs work for assemblies where applications rely on a stretched spring to pull the kinematic system bac to some setting. Compression springs work for assemblies where applications rely on a shortened spring to re-expand. Torsion springs work for assemblies needing application of torque.

Compression-type wave springs are by far most common. Single-turn wave springs can have overlapping ends to save axial space; nested wave springs deliver higher axial forces; multiple-turn wave springs are up to 50% shorter than a coil spring of otherwise comparable performance. What’s more, multiple-turn wave springs prevent torsional moves during compression — which is an issue with coil springs.

Material science looms large for wave-spring design. Some manufacturers tout the high strength and reliable performance of their springs. Many of these characteristics are quantified in terms of tensile strength, shear strength, modulus of elasticity, and more. The material from which the spring is made as well as the mode of wave-spring manufacture influence many of these values. Case in point: Some edge-wound springs made of flat wire can outperform springs stamped out of sheet metal, as their metal crystallites having long axes tending towards an orientation parallel to the spring’s curvature.

How to select a wave spring?

A basic formula helps design engineers specify wave springs and identify whether a design can use a standard spring — or require a custom wave spring. The dominant parameter is load to which the application subjects the wave spring. This load is the axial force the spring must deliver at its work height within the assembly.

Here is a basic formula to identify the wave-spring type, size, and shape that best suit an application. In fact, smaller designs and small-diameter wave springs (with diameters to less than 0.250 in.) along with material advancements are driving new applications for wave-spring application that’s more advanced than ever.

Some applications require multiple working heights so have critical loads at two or more wave-spring conditions. It’s often sufficient to use minimum and maximum loads for calculations, especially in motion assemblies requiring compensation for tolerance stackup.

Wave springs install onto shafts or into areas of the assembly machined as working cavities (internal bores). Piloting grooves or other geometry helps the wave spring stays in place. Distance between surfaces inducing load defines axial working cavity — and working spring height. This is where the spring’s material cross-section affects overall design.

More specifically, the factors dictating suitable wave-spring design include application load; bore geometry, shaft, ID, and OD; working height; and spring material to withstand environmental factors. Other general guidelines are that the wave-spring number of turns must be between two and 20; express the number of waves per turn in half-turn increments; minimum radial wall is three times wire thickness; and maximum radial wall is 10 times the wire thickness.

Reconsider working height for a moment: Designs must avoid situations that compress a wave spring to solid. That’s because as a wave spring approaches a height at which it becomes solid (with the various turns contacting or wave turns flattened) loads increase exponentially and even become unpredictable. These loads in turn can induce the spring to take a set or relax. Magnitude of relaxation depends on load and other application conditions. In any case, material deformation wll degrade spring performance.

More specifically, if a spring is going into a static application, ensure that percent stress at working height is less than 100% because springs can take a set or lose length loss under high stress.

If a spring is going into a dynamic application, ensure percent stress at working height is less than 80% because again — springs can take a set if subject to higher stress. If work height per turn is less than twice the wire thickness, the spring operates in a nonlinear range … and actual loads may exceed calculated loads.

Most manufacturers only test standard wave at the loads and work heights specified in literature. Usually they publish work heights that are the lowest recommended for a given spring … though other heights maybe possible. But contact the manufacturer for analysis of spring characteristics at alternate heights. Manufacturers can sometimes help OEMs design wave springs for applications that cannot adhere to normal guidelines.

Wave-spring technology advances to satisfy today’s applications

According to Sanjeev Rivera of Lee Spring, there are some industry moves towards design miniaturization. Wave springs excel here, thanks to the way they deliver a given spring force in significantly reduced space. So designers can reduce finished assemblies’ size and weight through use of wave springs.

Wave springs have also benefitted from new availability of raw materials and end configurations. Design engineers should consider these designs wherever applications are subject to weight or space restrictions. We often advise designers that wave springs in a sense act as stacked wave washers in series configuration — but without any worries about maintaining alignment. That’s because the wave-spring design maintains alignment on its own. Unique wave-spring variations such as nested and interlaced wave springs also exist to incorporate advanced fatigue and load-rating characteristics. Application of these geometries really depends on the assembly at hand.

Rotor Clip now offers interlocking spiral retaining rings to run at higher rpm

May 14, 2017 By Lisa Eitel Leave a Comment

Rotor Clip engineers regularly design custom parts and tools. Now one new iteration is an interlocking spiral retaining ring based on the manufacturer’s standard DCR non-interlocking spiral ring. The new Rotor Clip ring is made with a custom tooling process for producing DCR-LS interlocking spiral retaining ring.

DCR-LS advantages over standard DCR spiral rings are a resistance to tampering; higher rpm limits; and maintenance-free application. More after the jump.

Interlocking spiral rings are essential in gearboxes and other motion-system assemblies. The rings in these assemblies must stay in their grooves, even at high rpm. Rotational speeds high enough to make spiral rings move out of their groove can cause application failures. Here, the new spiral-ring locking mechanism ensures that the ring stays in the groove even at very high rpm.

Locking spiral rings minimize maintenance as well. Reconsider our gearbox example. Gearmakers maintain exacting levels of cleanliness during their manufacture and tightly seal these gearboxes to prevent contamination-induced damage. The designed gearbox components for minimal risk of failure. So here, interlocking spiral rings can eliminate maintenance in which personnel open the gearbox to replace parts — and risk contamination of the assembly in the process.

@RotorClip now offers interlocking spiral retaining rings to run at higher rpm #MadeInUSA link— Click To Tweet

Locking spiral rings also resist tampering, as they’re difficult for operators to remove from grooves — preventing many unauthorized or unnecessary machine adjustments.

For more information on DCR interlocking spiral retaining rings, visit rotorclip.com.

Power-transmission components and mechanical systems see three new trends

May 4, 2017 By Lisa Eitel Leave a Comment

Power-transmission (PT) components include essentials such as chain, springs, seals, and retaining devices, to name a few. There are three main trends that have dominated recent innovation in their design and application. New materials in mechanical parts continue to expand the applications in which all components operate effectively. Compression and wave springs are specified in more customized versions than ever, tying to a larger move away from off-the-shelf components. Finally, demand for longer life is spurring advances in lubrication to 21st-century formulations.

In fact, all mechanical designs must satisfy ever-changing industrial design needs, but here we detail advances that industry professionals see dominating these power-transmission assemblies.

Here Kevin McBarron at Nye Lubricants adjusts pins for an electrical-connector application test. Five engineers work in the 2,200 ft2 ADVT lab. Through their experience and knowledge, the supplier can now can model and simulate applications and make computational simulations for performance prediction. this lets Nye run three types of tests, depending on project needs — modeling and simulation, component testing, and practical testing.

IoT on belt drives and digital design help elsewhere

Internet of Things (IoT) and Industry 4.0 functionality is touching even mature power-transmission technologies to boost design performance.

“The rising tide of IoT could mean that larger (and more mission-critical) power-transmission drives could soon include widespread placement of sensors,” said Arron Ryan, product engineer at Thermoid, manufacturer of rubber products including belting and hose. “On conveyor belting as well as power-transmission belting, the sensors would fit onto pulleys to measure performance and wear factors — including changes in groove ride height and rates of efficiency,” Ryan continued.

There are already sensor systems available (albeit at higher price points) that can capture inputs such as run time, temperature, and vibration. “But technology enhancements such as this on a large scale could soon provide designers of drives with big data to design longer-lasting products with higher efficiencies and reduced maintenance,” Ryan of Thermoid concluded.

Another form of improved service from digital data is the proliferation of online configuration tools. These are changing how design engineers specify all offerings in the power-transmission and motion-control space — in part because service expectations in the industrial market are ultimately influenced by what’s come to be expected from the consumer market.

“Online configurators for clothing and other consumer products give users quick leadtimes and the ability to get price and delivery without ever talking to someone. Now these B2C online-purchasing trends are informing the design of configuration tools that have become integral to the B2B engineering-design process,” said Mike Parzych of GAM Enterprises.

Right now, a GAM online sizing tool lets engineers specify components that are compatible with their servomotor. The tool is integrated with an online catalog and CAD configurator. The manufacturer is also looking to add options and customizable capabilities to the latter. “Our products are configurable, and we want our models to reflect that,” said Parzych.

Visit linearmotiontips.com and read our trends piece on online configuration tools for more on what’s on the horizon here.

New installations for retaining rings and wave springs

Over the last several years, there’s been a slow trend to replace threaded fasteners (and the tapping and drilling they entail) with retaining rings. These fasteners installed into assemblies at preset shaft or housing grooves that function as shoulders to keep an assembly together. What’s more, material advancements continue to improve these as well as other spacers, pins, and washers.

Coatings of zinc thermal diffusion weren’t commercially viable for small components until recently. Now processes and equipment from SPIROL allow for this coating on small mechanical parts and fasteners. Shown here is a base layer of a part followed by alpha, gamma, delta, and zeta layers of the sacrificial zinc coating. Notice the uniformity.

Case in point: Finishing with affordable zinc thermal diffusion is better than ever for finishing parts with a sacrificial surface of zinc-iron diffusion. Now mechanical-component suppliers are applying one newer patented version of the process called ArmorGalv. Fastener company SPIROL is one adopter.

In short, ArmorGalv coating applies at 650˚ F or higher in a closed chamber. The part bakes in a closed environment filled with zinc vapor. Soluble in iron, the zinc diffuses into the ferrous part in a near-zero-emissions process. The coating is anodic to steel, so makes for long-lasting galvanic protection. After baking, sometimes the parts get additional application of sealant. Benefits include anti-galling, uniform coating, and no embrittlement.

Another trend affecting fasteners is the unabated drive towards miniaturized designs. This forces the shrinking of assemblies — including all their fasteners and compression and wave springs. Consumer electronics and medical-device industries are driving much of the innovation in this department.

In some cases, simply switching to compact compression springs or from conventional helical-wound springs to wave springs in sufficient. That’s because these apply more load for a given volume — which is useful in the tight spaces inside implantable medical devices, for example. In fact, even disposable surgical applications are driving engineers to design smaller instruments, as there’s more interest than ever in making surgeries less invasive. That’s turning many inpatient procedures to outpatient procedures — a win for all.

Behind some of this is how technological advances now let developers make wave springs smaller than 0.250 in. in diameter … enabling smaller tools in other industries as well. Even cordless drills and other consumer power-tool designs benefit.

Bespoke lubrication formulas (and mechanical design) for better PT performance

Some lubricant suppliers are looking to solve mechanical challenges from the tribological front — and they’re taking cues from an industry that’s increasingly service-oriented. “Several years ago, a new concept was born within our technical organization,” said Jason Galary, engineering development and applications manager at Nye Lubricants. The idea was to create technical competency and functionality for bridging a gap between R&D and product development. “This new functionality focuses on developing a better understanding of the fundamentals of applied tribology and combining this with simulations of customer applications,” explained Galary.

Here Jason Galary and Gus Flaherty of Nye Lubricants study data from their laboratory’s particle-generation tester. The ADVT lab is Nye Lubricants’ response to the trend towards increased in-house engineering expertise and support through collaborative efforts with end users to solve tribological problems.

Usually in industry, the supplier identifies or develops lubrication solutions for the OEM or end user, and then ships lubricant samples out to the customer for testing. Such tests are based on physical property data and the experience of technical support and sales engineers. But such an approach burdens the OEM or user with testing and upfront cost. “We moved away from this by creating Nye’s Applications Development and Validation Testing (ADVT) group,” explained Galary.

The ADVT lab now focuses on two modes of testing — component testing (and simulation) as well as applied mechanics.

“Through stronger understanding of how lubrication systems function in dynamic applications, we can more accurately predict performance and supply better lubricant,” said Galary. This helps users trim research, development, and testing time, in turn reducing product cost.

Consider one example for the semiconductor-manufacturing industry and how the lubricant supplier developed a particle-generation test method and apparatus.

Here, Kevin McBarron of Nye Lubricants lubricates a shaft for a steering system. Component testing is just one form of partnering to trim lubrication development time and cost for users. Recently, Nye designed a simulation rig around a full-size electronic power steering (EPS) system from customer specifications. Working with the parts manufacturer to develop an accelerated endurance test, the lubricant supplier devised a new formula to meet performance goals and boost system life and quality — so the tribological test validation was satisfied, and the manufacturer could focus development elsewhere.

“The thought of particle generation is one that haunts many engineers’ minds, especially if they’re working on applications in the vacuum industry,” said Galary. Foreign particles of unknown or dubious nature drifting through the air (or traveling through vacuum) might deposit on critical areas such as a semiconductor fab, and cause extremely costly problems as a result. “But our new test method measures the amount of airborne particulate generated by a lubricant from rolling contact as in a ballscrew or bearing,” said Galary. “That lets us classify a grease to an ISO or federal air-cleanliness standard.” That in turn lets users know just how many particles are being generated in their cleanroom, so they can pick a material to match their cleanliness requirements.

In fact, it’s not just the formulation of lubricants. All motion-component suppliers we surveyed mentioned some expansion of in-house engineering support. Some who supply mechanical-design services base much of their business on it — mostly to eliminate problems associated in the past with integration.

More motion-component suppliers than ever (including GAM Enterprises) act as extensions of customers’ engineering departments by helping them eliminate components, save space, and boost design performance. Listed here are some ways in which GAM components improve the design of one lift system.

“Customization is in GAM’s DNA. Our mission is to give customers what they want, even in small batches and at a value,” said Craig Van den Avont, president at GAM Enterprises, manufacturer of gear reducers, couplings, linear-mounting kits, and other automation products. The manufacturer works with design engineers to understand their application, requirements, and machine assembly. Then it seeks ways to combine or modify standard products (or manufacture other components) so OEMs or end users can build a better machine or optimize to application requirements.

“We’ve had to align all our business functions to properly support these projects,” said Van den Avont. Last year for example, the company expanded in-house manufacturing capabilities with customization and flexibility in mind. “Ultimately, we act as an extension of our customers’ engineering departments by helping them eliminate components, save space, reduce costs, and increase machine performance,” added Van den Avont.

Download the PDF: Metal shims brochure from SPIROL

January 29, 2016 By Lisa Eitel Leave a Comment

A new brochure from SPIROL details the breadth of the SPIROL metal shims product line … as well as value-added services and quality certifications.

Download the shims brochure at this spirolshims.com deep link —

www.spirolshims.com/SPIROL-Precision-Metal-Shims-brochure_us.pdf.

SPIROL specializes in quick turnaround delivery of precision-engineered shims ranging from simple OD/ID shapes to complex geometries — particularly in low to medium volumes.

All shims are custom-made to customer specifications from a comprehensive inventory of raw materials in thicknesses from 0.002 to 0.250 in. This new catalog details SPIROL product offerings and highlights the major ways the company can help customers improve their profitability when they partner with SPIROL on shim requirements.

The SPIROL Precision Shim product line includes specialty shims, thrust washers, laminated and edge-bonded shims in an array of configurations. Manufacturing processes and value-added services are performed in-house under SPIROL’s quality system registered to ISO 9001, AS 9100 and TS/ISO 16949.

The shims come in global industry-standard shim, sheet and coil stock, laminated materials and specialty metals in both inch and metric gauges. Passivate, zinc plate, cadmium plate, black oxide, anodized, and other finishes are available.

Metal shims application example: Industrial equipment

SPIROL supplies precision shims and thrust washers to leading industrial-equipment manufacturers.

The products go into prototyping and full production in myriad industrial applications — including those for production machinery, pulp and paper, oil and gas, and material handling.

Customization of shims and washers boosts flexibility for design and manufacturing engineers. From technical support to specialty products (such as edge-bonded shims and other kitting options) the manufacturer aims to take cost and complexity out of assemblies.

Motion systems application examples: Compression springs

November 26, 2015 By Lisa Eitel Leave a Comment

By Leslie Langnau • Compression springs are typically used to resist linear compressing forces (such as a push force) where space is limited, where uniform bearing pressures are required, or to reduce buckling.

Thus, they are ubiquitous motion components. In the automotive industry, they are common in seats, pedals, transmission springs and windshield wipers. More after the jump.

Shown here is a compression spring inside the ball of a Dyson vacuum cleaner. The spring helps a flexible changeover valve-hose assembly engage with the floor-vacuuming mechanism or the wand, depending on how the user moves the handle.

Building automation uses compression springs for industrial doors, fasteners and dampers. In electric-distribution applications, they are indispensable for the function of contact switches and other electromechanical components.

This application example from Jacquemet Group shows compression springs in an engine.

Medical uses for compression springs also abound—in simple mechanical equipment, such as beds, to those in advanced actuators for precision medical devices. In consumer devices, they are found in major appliances, lawn mowers, cell phones and so on.