Printing Inspiration: 3D Printing in STEM Education

The University of Illinois in Urbana-Champaign Makerlab is the world’s first on-campus Business School 3D Printing Lab, with sixteen Makerbot Replicator 2 printers available for use. But if you look through the door of this lab on a Monday night, it might not be college students you see hard at work designing and printing, but a group of 7-10 year old MakerGirls. Founded by three Illinois students, Lizzy Engele, Sophie Li, and Julia Haried, MakerGirl has set out to empower young girls to become leaders in STEM fields through 3D Printing, creative activities, and a presentation on women who have made contributions in STEM fields.

MakerGirls learn to use software to design their projects for 3D Printing

As a part of her business classes and internships, Co-Founder Julia Haried “noticed an inequality in C-Suite positions in STEM, with very few women in these roles.” While women make up almost half of the American workforce, only about 14% of STEM career roles are held by women. Fewer than 60% of girls have met a woman in a science, technology, engineering or math career. “While we knew we couldn’t have an immediate and direct impact at the C-Suite level (CEO, COO, etc.), we saw an opportunity to make an impact starting with younger girls”, says Julia.

A MakerGirl is hard at work on the designing phase of her project

According to Julia, MakerGirl chose 3D Printing as a way to get girls excited about STEM by highlighting a technology that is creative, on trend, and has the potential to revolutionize many industries. The printers are safe for kids and easy to operate, and the lab itself is “an amazing and valuable resource” to do so. Makergirl is not focused solely on the girls though, but also in helping parents to continue making STEM exciting at home by providing additional material to make learning a family-oriented and ongoing adventure. According to the US Bureau of Labor Statistics, the United States will need to fill 1.7 million job openings in Science, Technology, Engineering, and Mathematics (STEM) careers between 2012 and 2022 due to growth and replacement needs. While this is good news for both recent graduates and current students, it also provides parents an incredible opportunity to support and encourage their children’s interest in STEM classes and careers. “It’s important to get men to support this change as well”, adds Julia.

During a MakerGirl session, each girl has an opportunity to use the computers to design a project for herself and see it created on the 3D Printer. Projects have included bracelets, hair barrettes, and printed name magnets. As a part of the session, the girls also have an opportunity to interact with the lead engineers, typically female faculty members or engineering students, who talk to the girls about the contributions of women such as Marita Cheng (Founder of 2Mar Robotics), Marie Curie (Physicist, Chemist, and Nobel Prize Winner), Bessie Coleman (Aviator), and Ada Lovelace (Mathematician). The girls also get to learn about different career options available in STEM fields.

MakerGirls learn about the contributions of women in STEM fields

Sessions at MakerGirl have sold out within hours of being opened for registration, with a cost of $15 per session. As summer vacation approaches, MakerGirl hopes to quadruple the number of students able to attend sessions. The group is also on track to obtain 501(c)(3) status, with the goal in mind of partnering with other Universities to bring MakerGirl to campuses across the country. While MakerGirl can be modified to fit the resources of schools, the program is also looking down the road to obtaining and modifying a truck to take MakerGirl mobile. With a vehicle full of 3D Printer stations and computers, MakerGirl could have the potential to travel to elementary schools and colleges across the country to hold 3D Printing sessions on-site. According to Julia, “It’s a goal of ours, to have several trucks available across the country and share MakerGirl.”

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5 Ways to Build a Culture of Safety

Everyone agrees that the safety of workers must be a top priority within industrial manufacturing environments, but the exact methods that should be employed are more often the subject of debate. There are dozens of ways that a culture of safety can manifest itself within the business culture and the day to day activities of assembly personnel.   That being said, there are still a number of tangible actions that, upon implementation, will help to build a culture of safety within an industrial manufacturing setting which is already inherently fraught with dangers.

2014 Statistics Infographic by SafetySmart

• Engineer safety into Equipment: This is admittedly the broadest, albeit most important initiative.  The methods of employing this are only limited by the creativity of manufacturing engineers, and they include everything from the use of infrared light safety screens that disable equipment while the screen is breached to the use of controls that require two hands to use.  These types of features used with industrial automation equipment help reduce the effect of human error, and thus, the number of possible injuries.
• Don’t Forget Ergonomics: It’s also extremely important to provide ample working space between equipment fixtures/jigs. Ergonomic working conditions are essential to avoid most of the repetitive strain/fatigue related injuries that come with many manufacturing/assembly jobs.  Production lines must be designed with this in mind, and input from workers goes a long way towards catching additional ergonomic concerns that may have been missed.
• Build in Small Production Breaks wherever possible: Manufacturing and production work, in addition to being physically strenuous, can also sometimes be extremely repetitive.  Monotonous work done for hours at a time can inevitably lead to a dangerously fatigued workforce, which can be a huge driver of largely preventable accidents and serious injuries.  Although all fatigue will never be completely eliminated, small production breaks can go a long way to mitigating the concern by greatly reducing extreme fatigue.
• Mark Specific Transient Hazards: Post large, visible warning signs on potential hazards and block off areas that may possess a large amount of hazardous energy and pose a particular risk of personnel injury. A workpiece radiating heat hot enough to sear flesh may be invisible without a warning sign indicating the existence of such a hazard.
• Discuss Safety Daily: Safety is not something that can be forgotten until an accident occurs, as this leads to complacency that breeds the potential for accidents. The best way to flight this complacency is to openly discuss continuous measures of safety improvement.  Production managers must take it upon themselves to daily discuss safety issues and identify newly discovered safety concerns.   This will help to create a culture where workers feel comfortable identifying safety concerns as they arise during daily operations.

These tips and suggestions do provide a good way to get started by thinking more holistically about safety in industrial work settings, but the specifics of mandatory workplace safety standards and compliance cannot afford to be neglected either.   In the U.S., the Occupational Health and Safety Administration (OHSA), the governing body for workplace safety compliance, has an entire regulation section of their website that lists specific regulations for everything from PPE to the handling of hazardous materials.   At the international level, the International Organization for Standardization (ISO) has recently codified the much of the same standards and information into ISO-45001.  These standards, combined with the principles outlined above, provide the tools to forge a safe workplace.

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The Lowdown on Locating Pins

Locating pins are utilized in manufacturing setups to precisely position workpieces in various orientations to make it possible to execute a wide range of manufacturing operations or dimensional inspections.  Within this broad definition, the design of locating pins can be customized and optimized for a diverse mix of alignment needs as dictated by the manufacturing requirements.  For this reason, locating pins come in many different shapes and sizes and are fabricated from a wide range of specialized materials and coatings.  Additionally, in fast paced production environments, the time and effort involved in achieving this alignment also play an important role in the selection of the locating pin design; therefore, alignment schemes must be carefully designed to avoid lengthy setup times.  A brief survey of the types of pins and secondary features available for incorporation into pin designs will serve to open up new avenues for the manufacturing engineer to more effectively build alignment systems.

Head Styles

Locating pins are ordinarily differentiated by the shape of the pin head, with each head style accomplishing a slightly different purpose depending on the application.  A single diamond head pin, one of the most popular pin styles, contacts the mating hole at only two locations, allowing for ease of fit while still constraining all planar motion except rotation.  Cylindrical locating pins with generous lead in chamfers can be used where more precision is needed, but the use of these significantly increase set up time because cylindrical locating pin schemes are far more vulnerable to machining errors.  As the size and shape of the drilled hole depart from the specified dimensions, it becomes more difficult to mate the workpiece on multiple cylindrical locating pins which are designed to contact the mating hole at all points.  For this reason, an entirely cylindrical pin alignment scheme may not be necessary or practical.

In contrast, the diamond pin scheme can more easily be sized and is usually sufficient for most alignment applications.  A single diamond head pin can also be used in conjunction with a cylindrical pin to achieve an alignment scheme that is sufficient to quickly constrain a work piece to a high degree of precision. Additionally, when workpieces must be aligned to specified vertical clearances, height locating pins possessing a flat, hardened head and a tightly controlled length are typically employed.  In light of this brief survey, other head styles and shapes such as rounded, cone, and bullet style heads can also be specified as needed.

Shank Styles

The shank is the part of the pin that is installed into the mounting fixture and does not contact the workpiece.  A variety of different shank mounting configurations are available, such as the threaded shank for blind hole applications or shanks with various styles of side locating flats or notches for use when side access to the pin is available.  Shanks for press fits are also feasible when the back of the mounting plate can be accessed to facilitate the removal and replacement of the pin.  When access to the underside or side of the mounting plate/fixture is not feasible, various head mounting styles such as the counterbored pin are also available.

Other secondary features:

A wide variety of other secondary features and options are also available and can be specified to further hone the desired functionality of locating pins for each application.

Locating pins with machined flange features at the base of the head serve a dual functionality because the flange mates with the work piece and provides additional height location.

Stepped head pins, usually utilized in sheet metal fabrication, possess various diameter transitions at the head and allow for the positioning of numerous workpieces at once.

For blind hole positioning applications, locating pins with machined flat channels running down the pin head serve as an air vent system and are typically employed in tight fit-up applications in order to prevent air compression inside the hole.

Locating pins can also be fabricated with an undercut at the base of the pin which allows the work piece to actually rest on the base, should this be desired.   If this is not necessary, pins can also be fabricated with a generous radius at the head/shank transition in order to add structural strength to pins that may be subjected to substantial side loads.

Materials

Because locating pins are typically subjected to repeated, sometimes heavy contact loads, they are usually fabricated from hardened tool steels to achieve superior wear resistance when compared with softer materials.   In applications requiring a high degree of corrosion resistance, locating pins manufactured from 300/400 series stainless steels are available.

If the use of stainless steel pins are not feasible there are numerous engineered coatings which can be specified depending on the application, but a TiCN coating is most commonly specified to provide substantial corrosion resistance and harden the surface layer.

Additionally, other coating types can be specified to provide essential electrical insulation where locating pins are required to accurately fixture the workpiece in the pre-weld setup.  One of the most popular, cost effective options is the KCF alloy coating which provides excellent insulation and prevents weld build up between the workpiece and the pin surfaces.

Summary

As detailed in this brief survey of locating pin diversity and functionality, there are many features that can be combined into a locating pin design for a variety of applications.  The chart below represents a good starting point in summarizing the extensive number of possibilities available to the manufacturing engineer.  No matter the alignment application, there is a locating pin for the job.

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How to Choose between Linear Shafts, Posts, and Rotary Shafts

You may have heard the terms “linear shaft”, “post”, and “rotary shaft” before, but what are the differences between these terms, and which applications should you use them in? Don’t worry, we’re here to help!

Introduction

Linear shafts, posts, and rotary shafts are used when you need to control some type of motion, either linear or rotary, or a combination of the two. Before we dive into the motion aspects, let’s take a look at how each option works.

Linear Shaft and Bushing Image from MISUMI

• Linear shafts: The term “linear shaft” can be a little misleading, as the shaft isn’t actually doing any work – it’s just there for support. A linear shaft is used when a sliding motion is needed, especially when that motion needs to be guided and fine-tuned. The loads and requirements of the motion dictate the shaft size and precision. Feel free to reference our previous post on Sliding Guides for more information.
• Posts: A post is exactly what it sounds like – a cylindrical bar that is attached on one end to a base, and has something that rotates around it. Posts (commonly known as standoffs) are used to position components in machine designs or assemblies. They can also be used to separate or connect other components and can be found in round, hex and square shape.

Rotary Shaft Image from Wikimedia

• Rotary shafts: In the example above, the shaft is doing the work by turning and transmitting power. The shaft can act alone, such as the drive shaft of an automobile, or along with a system of pulleys and belts or chains, such as the pedal on a bicycle. Here, shaft sizing is determined by the amount of power that needs to be transmitted.

Choosing the Best Option (Defining Your Motion)

Now that we’ve covered the basics of each option, how do you choose between the three? Quite simply, the answer lies in determining the type of motion that you have in your application. Any kind of sliding or translating motion requires a linear shaft. However, if you need to transmit power over a distance, or if you need to adjust the relative speed of some rotation (see our article on Sizing Timing Belts and Pulleys), a rotary shaft is your answer. Finally, if you need to have a rotary motion that is fixed around a particular spot, such as an idler pulley, the simple post is a great solution.

Motorized Cable Reeler Image from Taymer

One application which can potentially utilize all three shafts is a motorized cable reeler.  As cable is metered onto the spool, linear shafts and bearings are used to evenly meter the cable back onto the reel.  Rotary shafts are employed to support the cable spool as it spins to meter out or retract cable.  Finally, circular posts are used as structural supports to support both the spool and the guide apparatus.  A comparable functionality can be found on a much smaller scale in modern fishing reels, where a guide is actuated back and forth – supported with a linear shaft – to evenly meter the line onto the spool.  A radial drive shaft is employed to spin the spool, and circular posts are employed as structural supports.

Conclusion

As with a lot of engineering problems, identifying the type of motion is the most critical aspect of the design. Once you have that knowledge, choosing between linear shafts, posts, and rotary shafts is quite easy.

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Ball Screw Lubrication Tips: Application & Grease vs. Oil

When you forget to change the oil in your car’s engine, it won’t take long before you start having numerous other engine problems. Without the oil to lubricate the metal-to-metal contact, your car’s engine will get hot and dirty, parts will break, and it may even seize up to the point of needing costly major replacements.

Letting your ball screws go without scheduled lubrication and ignoring the grinding metal-to-metal contact essentially has the same effect as not changing your engine oil, and usually results in hours of unanticipated downtime servicing your workplace machinery.

Ball Screw Wear Image by Machine Design

Fortunately, keeping a constant thin film of lubrication, oil or grease, solves a multitude of unwarranted problems and extends the screw’s life and work efficiency by reducing friction and minimizing torque.

Applying LubricationBefore you apply any lubrication, whether you choose grease or oil, make sure the ball screw is thoroughly clean and dry. Get rid of any buildup from the grease or oil that’s been sitting over the past few months so it doesn’t get caught between the balls or on the screw leads, damaging the screw and its connected parts.

Don’t apply too much lubrication at once. Rather than a ball screw that is dripping wet and creating a mess on the rest of the machine, make sure that the screw is simply wet to the touch – having just enough lubrication to prevent dry metal-to-metal contact.

Grease vs. Oil

Knowing that you need to lubricate your ball screws on a semi-regular basis is only half the battle. The other half is figuring out exactly which type of lubrication to use.

Oils are sometimes considered lower-maintenance than greases, since they’re less likely to create a buildup and tend to stay inside the ball nut much better than greases do.

Oils usually require a pump and filtering system, and work well with low to moderate operating speeds, load sizes, and temperatures. However, if any of these three factors are too extreme, it can render the oil coating useless, causing metal-to-metal friction and damage.

Greases, on the other hand, can go directly onto the screw itself or into the ball nut if it has open holes to pump the grease through. Greases can also handle high speeds and be used with additives to create synthetic lubricants that can handle more extreme temperatures, load sizes, and speeds. However, greases shouldn’t be used with molybdenum disulfide or graphite since they create friction levels that are actually too low.

Our Product RecommendationsAt Misumi, we recommend lubricating ball screws with a normal workload every six months and ball screws with a heavy workload every three months. The friction and rolling resistance between the grooves and the ball bearings stays low when you re-lubricate at this frequency, especially if you carefully select the right lubrication for your specific job.

We offer three types of grease specifically tailored for different types of working environments:

• L Type: linear ball bushings, stroke ball bushings, linear rotary bushings
• G Type: linear miniature guides
• H Type: linear guides, precision ball screws, rolled ball screws

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