How to Select Industrial Products

This is the place for engineers to learn about and teach others how to select industrial products. The blog is maintained by the Editorial team at IEEE GlobalSpec, the company that powers CR4.

Trying to Find 'Fabulous' Light Curtains

Posted April 01, 2013 6:05 AM by HUSH
Pathfinder Tags: how to select light curtains

I really wish they would make light curtains available in more colors, don't you?

Their appearance always clashes with the machinery. The silver and black parts picker looks HORRIBLE next to those yellow light curtains. Some people say black is neutral--but me, honey please! Don't even get me started on these orange coveralls! I say there is nothing wrong with being fabulous while also doing a little hard work.

So is the life for that fashionably-perfect in the manufacturing world. However, those light curtains do keep this tight tush nice and safe.

A light curtain's main advantage is that it does not impose a physical barrier on personnel. As such, an operator is able to access guarded components without mechanical or observational limitations. Maintenance processes are also eased by their use. Light curtains can be used to monitor cargo in or out of a restricted access area, as well as provide strictly one-way access.

A transmitter is established and an array of parallel infrared beams provide a boundary across the restricted access point. The transmitter can emit its rays in virtually any configuration provided the infrared beams conclude at a receiver. Mirrors are frequently used to relay beams around corners or obstacles which reduces the need for multiple transmitters, but for every mirror the beam range is reduced by 25%. An alignment laser or LED indicator is frequently integrated in the transmitter for accurate positioning. Manufacturers may elect to incorporate light curtains in standalone machinery and these devices will have increased sensitivity. Light curtains have variable and convenient installation patterns.

The infrared light beams are sequenced and modulated and the receiver is designed to recognize a specific infrared beam, decreasing the chance for issues from ambient infrared light. When a beam is obstructed by an opaque object, a safety relay halts the machinery or process within milliseconds. Some light curtains allow the process to resume once the obstruction is removed, while others require an operator to manually restart the process. A PLC (integral or external) is required for the light curtain to interface with the machinery it encloses. A timed mute feature allows operators to control the flow of materials through the perimeter without stopping the machine. Some muting scenarios allow the passage of humans, while if other muting sensors register a human or irregularity then the process will cease.

And while it may not be available in say, polka dots or glittery pink (my fave!), many light curtains offer much more important features. Self-checking circuitry has the capability to run a self-check during startup, operation, or continuously to ensure no loss of function. Latching safety relays will not remove the stop signal until the controls are manually reset outside the protected area. And muting is the temporary, automatically controlled deactivation of a safeguarding device during the non-hazardous portion of the machine cycle.

Anyhow, you can learn all about light curtains at the GlobalSpec Light Curtain Selection Guide. And though the search filter doesn't have a category for color, it can be useful for some other solutions.

Excuse me, time for lunch with the boys from floor 3 . Ciao!

(Images credits: Southern Industrial Equipment; Industry Direct)

2 comments; last comment on 04/03/2013
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Scissor Lifts Make Great Toys

Posted February 25, 2013 8:00 AM by HUSH

So many industrial products and process find alternative uses in the arts.

Paint isn't just a surface coating, but a means of visual expression and interpretation. Modern art sculptors have been using welding and brazing techniques for decades to create obtuse structures. Steampunk has become a clothing and aesthetic style that idolizes 19th Century steam-powered machinery.

And, in what is perhaps the performing art's introduction to industrial machinery, scissor lifts now participate in ballet. No really, have a look.

While as, um--beautiful, as that was, it's likely that the composer was simply living out a childhood fantasy of playing on scissor lifts. They do look like giant toys after all. It's unlikely though that the composer understood the industrious nature of his playthings.

Scissor lifts owe their mechanical capability to the pantograph. A pantograph is a series of linked parallelograms with hinged intersections that allow the operator to elongate the mechanism while still maintaining the integrity of the geometric figure. The structural components of the pantograph serve as opposing line segments within adjacent parallelograms; geometric changes are therefore uniform across the mechanism. True vertical lift is accomplished by using components of equal length.

When two pantographs are arranged so as to actuate from a single drive they extend correspondingly and loads can be balanced between them. A calculator exists for computing the linear input force required according to where the drive supplies power to the scissor mechanism, be it upon the base or a center pin .

Motor-driven propulsion is a valuable attribute in many situations requiring scissor lifts. This allows workers to position the lift on an as-needed basis which is particularly useful in maintenance and construction applications. 'Slab' lifts are restricted to paved, smooth surfaces; rough terrain lifts rely on robust tires and four-wheel drive to traverse off-road conditions.

To improve lift agility, manufacturers rely on a sharp turning radius and a short wheelbase. Parking brakes ensure lift location, and tires and casters come in non-marking, off-road, anti-slip, press-on, and urethane varieties. Economical and legal reasons prohibit scissor lifts from road travel; they are hauled or towed between job sites. However, some scissor lifts may be flatbed or railcar-mounted for specialty applications. Many mobilized lifts utilize outriggers for further foundational stability.

Furthermore, the control, maneuverability, and power source of a scissor lift is critical to its utility, other characteristics better describe the vertical capabilities of the lift.

  • Stroke: this is the range of height safely attained by use of a scissor lift. This is directly correlated with the number of scissor intersections and the length of the components used in the pantograph.
  • Size: this is the dimensions of the work platform elevated by the lift. Many lifts feature an extendable platform to increase the area's square volume.
  • Capacity: the maximum burden that the lift is designed to safely support, be it personnel or freight.
  • Tilt: in cargo-lifting situations it may be helpful to have a lift table that can pitch its load to an angle to make the load more accessible.

You can see IHS GlobalSpec's complete scissor lift selection guide here.

Also, if you have a scissor lift, remember that you should not operate it with your judgment impaired or on the road, like this idiot [language].

(Image credits: Wikipedia; Taylor Rental; IHS GlobalSpec; Craig Boyce)

2 comments; last comment on 03/02/2013
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How to Select Rotary Switches

Posted February 04, 2013 3:59 PM by Chelsey H

Rotary switches move in a circle and can stop in several positions. They are used to control many different circuits or select different valves for one circuit with a single switch. These devices have some advantages over other switches since turning the actuator can turn circuits on or off depending on the position and many different actuation positions are possible. Rotary switches can also be designed to have many contacts happening at once on a single switch position. While rotary switches can be found on many types of industrial equipment, they can also be found in consumer equipment such as in a car for adjusting things like fan speed. Rotary switches are becoming less common since complex switching operations are being done with digital equipment such as touchscreens. Mechanical rotary switches are still used however, especially in equipment where a computer failure could be a safety issue. Image Credit: Omega Engineering

Rotary switches have a rotating spindle. The rotors are on a spindle and each rotor has an arm projecting outward that can make contact with a terminal when the switch is in a certain position. Depending on the number of rotors, the switch can have dozens of different positions and each one can be attached to a particular circuit.

Parts of a rotary switch. Image Credit:

In order to put the rotary switch in the proper position, a detent mechanism is used. This mechanism makes the switch "click" into position and stay in place until enough force is applied, preventing the switch from turning freely and being put in the wrong setting accidentally. A detent uses a wheel with notches or grooves cut into it and attached to the rotor. When the wheel reaches the correct position a spring-loaded ball bearing or piece of spring steel pressing against the wheel presses into the groove holding it into place.

Important physical switch specifications to consider when selecting a rotary switch include mechanical life, number of poles, angle between positions, number of decks, number of poles per deck, and switch frame.

Multi-deck (left) and Single deck (right) rotary switch Image Credit: Elma

Number of poles per deck- The number of poles per deck is the number of separate circuits that can be activated through a rotary switch per deck. The output connections are usually called ways instead of throws. The construction of the switch provides a total of 12 ways but there may be 1, 2, 3, or 4 poles. The rotating contact will channel the signal from the pole to the output terminals. The number of terminals required determines how many positions a switch will have.

Stop Style

Rotary switches with an adjustable or continuous stop are commonly available. The stop style should be selected based on the need of the application.

Adjustable stops give the user the option to stop when desired. Adjustable stops allow the user to take a 12-position switch and adjust it to have any number of positions between 2 and 12. This stop should be used for low volume requirements.

Continuous stops, also known as no stops, do not have any stop positions on the rotary switch.

Fixed stops have the stop positions come fixed from the manufacturer and are not changeable by the user. They are better for volume production requirements so the user does not have to adjust the switch.

For more information on Rotary Switches please read IHS GlobalSpec's How to Select Rotary Switches guide.

1 comments; last comment on 02/04/2013
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Do You Even Lift Table?

Posted January 21, 2013 10:42 AM by HUSH

Noble CR4 reader, allow me to introduce you to the internet.

It's this figurative place where people congregate on various interwebs to make snide remarks, argue with other information super-highway travelers, and look at pictures of cats and naked people.

Oh, you're well-versed in this technology it seems! I suspect you're here for the former two then, because CR4 is woefully empty of the latter two. Stick with me here, please.

Then do you know what a meme is? More specifically, DO YOU EVEN LIFT, BRO?

Excuse me, my inner lunkhead is coming out. Memes are visual placards expressing ironic or subtle humor relevant to internet culture.

The meme which we are discussing features musclemen refuting non-musclemen simply because they do not work out enough.

The origin of this strange, internet-insiders joke is closely intertwined with the existence of the lift table. See, lift tables are known for their robust capability and reliable work ethic. More specifically, they are devices that allow materials and workpieces to be raised and lowered to ergonomic and accessible heights for specific tasks or purposes. Despite its exclusive function lift models vary by size, capacity, elevation and actuation.

Furthermore, lift tables are often manufactured with wheels allowing operators to convey items at their discretion. These wheels are typically pressurized inner tube or urethane caster in design. Wheeled tables typically feature a handle for safe grasping as well as a floor lock to temporarily immobilize the table. Elevation control is usually provided by a hand or foot control, and some models may feature electronic integration. Versions that also feature a tilting table will rely on similar interfaces to determine the pitch of the table plane. Adjustable-speed ascent and descent can be popular features when dealing with dynamic, uncentered, or shifting loads such as liquids. Such loads also benefit from an integral counterbalance and retainment edges. Finally, models incorporating a carousel into the design allow operators to rotate cargo without unloading.

The four most important considerations when deciding upon a table lift are:

  • Capacity: The maximum weight the table is suitable to burden. Tables capable of lifting 5 [short] tons or more are common.
  • Size: The physical dimensions of the lift table.
  • Stroke: The elevation capability of lift table, from contraction to full expansion.
  • Operational manner: The power source and mechanism providing lift to the table.

How does a lift table get turned into an internet gag? By a musclehead getting into a lifting contest with a lift table--and losing.

Internetters everywhere were enthused at the sight of the musclehead getting beat by machinery--mostly because the musclehead was a jerk. The disembodied voice of the lift table became the rally cry of millions.

The lift table smugly asks the musclehead: "Do you even lift, bro?"

(Image credits: Toph the Tomboy; Funky Junk; Northern Tool; Brobible; Advanced Handling)

1 comments; last comment on 01/21/2013
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How to Select Industrial Gases

Posted December 24, 2012 12:00 AM by Chelsey H

Industrial gases encompass a large number of products that are gaseous at room temperature and pressure, and while they may actually be stored as a liquid or solid they are commonly used in gaseous form. Gases have unique properties and characteristics depending upon such variables as the temperature, pressure, and volume to which they are subjected. Gases have low densities, assume the volume of their containment (or dissipate to the atmosphere), mix well with other gases, and are more compressible than solids and liquids. Industrial gases are comprised of elements, molecular compounds, or mixtures.

Industrial gas suppliers typically provide the gas as well as the storage and processing equipment necessary to facilitate transportation and proper usage. Industrial gas equipment may include storage tanks and distribution systems, vaporizers and pressure vessels (dewars, cylinders, and tanks), and cryogenic trailers. Each of these items typically include a means of controlling pressure and flow.

Image Credit: NeonSigns012

Physical Properties of Gases

As mentioned earlier, gases are compressible and as such, knowledge of the pressure generated by a gas as it relates to temperature and volume are critical to any application from both a performance and safety perspective.

From a performance perspective, knowledge of the boiling point and freezing point may be relevant but the auto-ignition temperature, the minimum temperature required to ignite a gas or vapor in air without a spark or flame present, is of paramount importance.

The flammable (or explosive) range is the range of a gas or vapor concentration that will burn or explode if an ignition source is introduced. Limiting concentrations are commonly called the lower explosive or flammable limit (LEL/LFL) and the upper explosive or flammable limit (UEL/UFL).

Image Credit:

Application and Use of Gases

Industrial gases are used in a myriad of applications that are dependent upon the many unique properties of specific gases. For example, industrial gases are commonly used in manufacturing, especially in cutting and welding applications. Acetylene gas is a highly flammable gas used in such applications as the production of organic compounds such as neoprene and rubber. It may also be pressurized to produce benzene. Oxygen acetylene torches mix oxygen and acetylene gas in controlled amounts to produce an extremely hot flame. Oxy acetylene welding is used to cut steel or weld iron, and can produce a flame as hot as 6300° Fahrenheit. Other cutting devices include carbon dioxide lasers. CO2 laser cutting uses a laser beam focused with a lens to cut materials and is typically used for precision applications such as laser surgery. Rare industrial gases such as argon are also commonly used in laser applications.

Major applications include:

  • Calibration Gas / Gas Standard - a defined gas concentration used to establish the response curve of an analyzer.
  • Chemical Process / Petrochemical - pure gases, gas mixtures, or gas standards for reactions, water treatment, sterilization, instrumentation calibration, heating, and processing in the chemical, petrochemical and pulp and paper industries.
  • Electronic and Semiconductor - specialized for microelectronic manufacturing or semiconductor processing applications such as thin film deposition (CVD, PVD), etching, RTP, packaging, or soldering.
  • Environmental Monitoring - reference for compliance with regulatory mandates.
  • Food & Beverage / Packaging - food and beverages require gases for storage, ripening, carbonation, to minimize oxidation, sustain freshness, and more.
  • Laboratory / Analytical - used to ensure a uniform and/or inert environment for research, quality control, analytical work, and other laboratory needs.
  • Laser Gas - lasers require special gases to create a laser beam.
  • Pharmaceutical / Medical Gas - used for patient care, surgical procedures, and therapy.
  • Welding / Thermal Process Gas - high temperature processes require gases with a high energy content and low flash point.

Major Industrial Gases

While there are literally thousands of available industrial gases, certain industrial gases are major elements of the world economy. Major gases include:

Hydrogen (H) - a colorless, highly flammable, gaseous element.

Nitrogen - a nonmetallic element that constitutes nearly four-fifths of the air by volume. It occurs as a colorless, odorless, almost inert, diatomic gas (N2), in various minerals. Nitrogen is found in all proteins and used in a wide variety of important manufactures

Air - a colorless, odorless, tasteless, gaseous mixture; mainly nitrogen (approximately 78 percent) and oxygen (approximately 21 percent), with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases.

For More information on Industrial Gases, check out IHS GlobalSpec's Selection Guide.

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