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Industrial Engineering

MMH Solutions Webinar Q & A

Thank you to those of you who attended yesterday’s webinar on material handling solutions. We had a lot of fun presenting the material and hope you found it worthwhile. There were some great questions that came in and we’ve summarized our responses below. As always, if you have additional ideas or products to share with us, please do!

Q: Aren’t “overuse” injuries (e.g. wrist tendinitis in an office worker) also “overexertion” injuries, and are these included in these stats?­

Great point.  Repetitive motion injuries were also included in Liberty Mutual’s 2012 Workplace Safety Index.  They accounted for about 4% or $2.02 billion of injury costs to companies. 

Q: ­Can the full OHIO website be provided by email, I only got part of it.

The Ohio Bureau of Workers’ Compensation Lifting Guide is another great tool to assess some of the MMH tasks where you work, to make sure that our employees are protected from ergonomic risk.

Q: ­If I push a cart normally, but want to measure the push force w/ a fish scale, I assume I can measure w/ the fish scale pulling and that will also tell me the pushing force? ­

That is right.  We also recommend turning all swiveling casters 90 degrees to simulate the worst case pushing force.  Remember to get at least three measurements to ensure accuracy.

Q: ­For loading water bottles onto water coolers, I’ve seen a powered lift for the bottle but are the simpler solutions to this problem that you’ve seen?­

Remember the ‘comfort zone’.  If possible store the bottles above 24″ (the bottom of the comfort zone).  I have seen companies block the bottom shelf, or raise the entire storage unit above 24″.

Q: ­Where did the Cart Guidelines come from – research?­

We base all of our design guidelines on scientific research.  One resource we used for cart design is “Pushing and Pulling Carts and Two-Wheeled Hand Trucks” by Jung, M., Haight J., Freivalds (2005).

Q: ­do you have a reference for your cart guidelines – load >500lbs   I am assuming the 500 lbs is the load on cart not the cart and load weight­?

You can see the reference above for the publication.500 lb does represent the load on the cart. What we have found is that if you have less than optimal conditions (poor handle design and flooring) then having a load of greater than 500 lb will generally result in a push/pull force above suggested guidelines.  As always, remember it is best to measure that actual push/pull force and compare to such tools as Liberty Mutual Push/Pull tables.

Q: ­The lift and turn tables can be very expensive. Are there specific guidelines for when we need to put one in? Or a way to justify it?­

Cost justification can be made by looking at time savings.  If our employees are not “wasting motion” they are probably saving time, resulting in higher productivity.  There are many tools that can help measure that, one is Humantech’s STEP analysis.  You can also use the NIOSH lifting equation to evaluate the acceptability of the lifting or lowering task.

Q: What are your ­thoughts on back belts?

Back belts do not help eliminate the exposure to the MMH risk.  The solutions that we focus on will help reduce or eliminate one side of the ergonomics ‘fire triangle’ force, frequency, or posture.

Q: ­Who manufactured the three carts you showed (trash dumper, etc.)?­

Powered lift and turn cart – Southworth Products

Six-wheeled electric cart and trash dumper – ERGOdynamics

Q: ­A lot of this seems geared toward a fixed site.  We are a water utility. Our guys are in the street then move on.  Can some of this lift assist stuff be more portable?  ­

Consider a portable work platform dolly.  Our clients have had good success with using the Mule Lift Truck.

Q: ­Groups who work in remote sites often suffer shoulder injuries due to repetitive movements, has there ever been research that speaks to elevator lifts for extended heights > 40 steps for the average 15 gal buckets?­

We aren’t aware of any research addressing this issue specifically for handling 15 gallon buckets.  My gut inclination is that there are probably several issues involved (heart rate, WMDS, trip/fall hazards) in this work task and multiple analyses would be needed to provide a clear picture of the risk to the worker.

Q: ­We use 48 lb motor and orders range from 5 to 50 pieces. What out of the applications you showed today would be recommended from getting these from pallets to workbenches with or without carts?­

Many of the lift assist devices can accomplish this task.  You may have to work with the manufacturer to engineer an appropriate end effector for you specific application. We have had good luck with ball roller tables and stabilizing clamps mounted to hand truck.  The Equipois mobile cart we showed during the webinar seems like a good fit for your needs.  Here is a link to an online summary of the solution, which shows a sample configuration, a video, and rough costs.  

Q:  What are some vendors for pneumatic lift tables?

Southworth Products offers a pneumatic lift table.  The tables can range in capacity, reaching up to 4,000 lb.

Q:  What is the approximate cost of the dolly assister I see on the steps?  How heavy is it?  I’m thinking about lifting it in and out of a truck.

You can find lightweight dollies for between $100 – $200 through suppliers like Northern Tool and Equipment  or find stair climber that bolt on to existing dollies from Uline or Magliner.  There are many other vendors for these products.


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Posted by humantech on May 9th, 2013

Ergonomics Improvement Inertia

by Mike Hoonhorst, AEP

Recently I facilitated a RAPID Team Event® at a manufacturing company.  The format of these events is to train participants to identify ergonomic risk using Humantech’s Ergonomics Hit List®.  This empowers the employees to quickly see ergonomic risk factors in the workplace.  Once trained, the participants apply these principles to identify issues and brainstorm potential solutions.  The solutions are aimed at being low cost and high impact.  With some maintenance and facilities support, the solutions can be implemented in one or two days.

So we hit the floor.  We all stood around a workstation watching the operator work.  Interviewing the operator and identifying awkward postures and other ergonomic risks  is the first (or “Find It”) step.  Then came the “Fix It” part.  This is where all momentum seemed to stall.  The group turned to me and asked, “What can we do?”  I gave them one or two ideas, and then I could see the light bulbs turn on!  At that point, they were unstoppable.  In fact, I had to limit the amount of improvement ideas at 40, reminding them that we actually had to follow through!  It became very apparent to me that sometimes great ideas need to overcome inertia.  And once they do…watch out, your workplace will never be the same!


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Posted by humantech on March 6th, 2013

Webinar Q&A: Ergonomics for Manual Material Handling

We were so excited to have such a great turnout for our web course this week, Ergonomics for Manual Material Handling. Below are the answers to questions asked during the event.

Q: ­Are you going to talk about frequency independent lifts?­

A: This feature of the NIOSH lifting equation is very important because it calculates the recommended weight limit (RWL) without the influence of frequent lifting. Therefore, the frequency independent RWL provides the not-to-exceed weight of a load within an 8 hour period.

Q: ­In one of Humantech’s applied ergonomics manuals, there are some rules that explain how to determine duration.  Could you please speak to that?­

A: Duration is based on the patterns of continuous work-time and recovery-time periods. A continuous work-time period is defined as a period of uninterrupted work. Recovery-time is defined as the duration of light-work activity (e.g. sitting at a desk or table, monitoring operations, light assembly work, etc.) following a period of continuous lifting. Duration can be classified into three categories; short, moderate, and long.

Short duration is when an operator is lifting objects with work durations of one hour or less, followed by a recovery time equal to 1.2 times the work time. Moderate duration is characterized by lifting objects for greater than one hour, but not more than two hours, followed by a recovery period of at least .3 times the work time. Finally, long duration pertains to lifting durations between two and eight hours, with stand industrial rest allowances (e.g. morning, lunch, and afternoon rest breaks).

Q: ­ When you are unloading a pallet, what scenarios do you consider to use the equation? ­

A: This type of task should be analyzed by the composite NIOSH lifting equation. The composite NIOSH is similar to the standard NIOSH in that it produces a recommended weight limit and corresponding lifting index, but differs because it combines up to 10 sequential lifts at a time. A good method to adopt, when applying the composite NIOSH to a task such as this, would be to enter in the measurements for the closest, lowest position on the pallet. Second, you would measure the next closest, lowest position and then the furthest, lowest position. Continue this same method for the middle and top row of objects on the pallet to get a comprehensive view of unloading the pallet. The composite NIOSH will compile up to 10 separate lifts and create a single recommended weight limit and composite lifting index.

­ Q: ­ Can you repeat what you said about the operator choosing to twist versus must twist in using the NIOSH calculator?

A: During the webinar, we were discussing ­the difference between an operator needing to twist their torso in order to access an object and choosing to twist because they did not want to move their feet into the appropriate position. Often times we observe the latter of the two because the object is within an arm’s reach of the operator but at an angle of which the operator does not perceive it to be unsafe. In either case, the root cause of both of these situations is due to workplace dimensions.

Needing to twist to the torso in order to access a load is typically due to a lack of space provided for the operator. Contrastingly, choosing to twist is due to a lack of utilization of the space provided. These issues can be resolved if one ensures that the workplace is designed using industry standard design guidelines. Many sources are readily available including Humantech’s Handbook of Ergonomic Design Guidelines.

Q: ­We load material rolls on unwind spindles. Is there a push pull calculator for this task?­

A: No, you would perform the NIOSH lifting equation while loading the material rolls to their staging location. Then, you would use the Snook and Ciriello tables to analyze any pushes or pulls necessary to move the spindles throughout the facility.

Q: ­What is your definition of restricted areas that the NIOSH equation cannot be used for?  ­

A: A restricted work space is any area within the anterior, posterior, medial, lateral, and vertical planes that would affect an operator’s natural ability to lift/lower a load. For example, if a maintenance worker needs to remove a 35-lb guarding plate from a piece of machinery, the NIOSH should not be applied if there were objects impeding a clear path of lifting/lowering the guarding throughout the movement.

Q: ­What if the frequency is less than .2 lifts/min (1 lift every 5 minutes)?   For example one lift every 35 seconds (20 lbs)?  Do you use that above category (.2)

A: Yes, the frequency would be set at .2 lifts per minute for any lifts that are performed faster than every 5 minutes.


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Posted by humantech on February 22nd, 2013

Q & A From Material Handling Webinar

by Christy Lotz, CPE

Thanks to those of you who attended our Ergonomics for Manual Material Handling webinar last Friday.  There were some questions that we did not have time to get to during the event, but we have posted our answers below.  If we happened to miss one of your questions, feel free to write in a comment and we will get it answered.

What were the 3 ranges of the Lifting Index -  Red, Yellow, and Green?

Green represents a lifting index under 1.0

Yellow represents a lifting index between 1.0 and 3.0

Red represents a lifting index greater than 3.0

We have a process in which the operator does not lift the load but needs to twist the back to move it.

The NIOSH Lifting Equation was designed for lifting/lowering tasks and is focused on back burden.  However, there are a number of assessment tools available that focus on multiple body parts, and risk factors such as Posture, Force, Frequency and Duration.  Using an assessment tool like Humantech’s BRIEF™ (Baseline Risk Identification of Ergonomic Factors) Survey or REBA (Rapid Entire Body Assessment) would be the best option for the scenario you described.

Please explain the time factor which appears to increase the load limit for NIOSH.

The two “time” factors you may be referring to, are the frequency and duration. Frequency refers to the number of lifts per minute (minimum = 0.2 lifts/minute, maximum = 15 lifts/minute). Duration refers to the amount of total time spent lifting (< 1 hour, < 2 hours, < 8 hours).  For instance, if you lift a box 480 times per 8 hour shift, the frequency would be 1 lift per minute, and the duration would be 8 hours.

At our workplace, like many others, we have an aging workforce, which of course can present problems and more ergonomic-related injuries.  Do either of these tools account for an “age” factor?

This is definitely something that should be considered.  Currently, the equation shown does not account for the aging population, and you’re right that it may make an impact and should be considered.  There are a lot of factors that we have to be cognizant about when faced with an aging population, such as strength, vision, hearing, and cardiovascular demands.  Humantech will be addressing a few of these concerns and recommendations in a webinar in May.

If you are using a cart with only one set of casters that swivel, and the other two casters do not swivel, where should the casters that swivel be located on the cart – front or rear?

Front wheels should swivel for pulled carts, and back wheels should swivel for pushed carts.

Does the NIOSH lifting equation rely on a certain coefficient of friction between the person lifting and the floor?

The NIOSH Lifting Equation does not take into consideration the standing surface.  It assumes a “dry” surface.  Therefore, a slippery surface would increase risk/burden from an ergonomic and safety perspective and you would be underestimating the risk to the operator.

Why does the HT LiftCalc app only have 15 degree increments for angle of assymetry?

During the webinar, we mentioned that Humantech has a  NIOSH Lifting Equation application (HT NIOSH Lift Calculator).  In order to make it easier to use, we had the angle toggle increase by 15 degree increments (0 to 135 degrees).  Changing the angle by one degree does not have a significant impact, if any, on the overall score, so it was decided that it was determined that this would be easier for users.

What is the best tool to analyze a no-lift process?

There are a number of free assessment tools available that can be used to analyze all body parts with exposure to tasks that do not just include lifting.  For instance, REBA, WISHA (Washington State Checklist for Work-Related Musculoskeletal Disorders), RULA (Rapid Upper Limb Assessment), Job Strain Index etc.


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Posted by humantech on January 30th, 2012

Product Review: zeroG

Product Name:

zeroG® Mechanical Support Arm

Description:

For the past couple of years, Equipois Inc. has revolutionized the ergonomics world with its patented zeroG® mechanical support arm technology that has quickly found itself to be a highly beneficial resource in applications across multiple manufacturing zeroGenvironments.  These include but are not limited to: overhead sanding, component grinding, riveting, welding, drilling, and a range of other manufacturing processes.  The latest model, the Equipois X-Ar exoskeletal arm support is a wearable device designed for tasks where people work with their arms outstretched for long periods.

Ergonomic Benefits and Features:

  • Makes heavy tools, parts, and other loads almost negligible.
  • Extreme freedom of motion when manipulating the arm.
  • Simple to learn and intuitive to control.
  • Reduces forces placed on the upper body when working with outstretched arms or heavy objects.
  • Requires minimal maintenance and is easy to integrate into existing equipment as retrofits and/or add-ons.

Potential Limitations:

  • Requires adequate space to use device.
  • Not yet able to accommodate quick changes for various weight loads within task, however, settings are adjustable to any specific load.

Applications:

  • Aerospace
  • Automotive
  • Heavy Machinery/Equipment
  • Manufacturing
  • Doctors
  • Dentists
  • Drilling
  • Grinding
  • Riveting
  • Sanding
  • Welding

Humantech does not endorse any of the products or companies featured in the reviews. All images are property of the vendor and used for illustrative reference only.


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Posted by humantech on October 13th, 2011

Q&A from Material Handling Webinar

Christy_lotz_2x2_300dpi Submitted by Christy Lotz, CPE

I recently facilitated a webinar entitled “Ergonomics for Manual Material Handling”.  There were a lot of great questions; some of which we didn’t get a chance to answer during the session.  For those questions, I thought that it would be helpful to post the answers up here on our blog.

What is “overexertion” and is OSHA record keeping required?

During the webinar, we mentioned the Liberty Mutual Workplace Safety Index. They define “overexertion” as “injuries caused from excessive lifting, pushing, pulling, holding, carrying or throwing”. They get the majority of their statistics from the Bureau of Labor Statistics who in turn gets their information from OSHA and Workers Compensation.  The statistics I was quoting were based off of missing six or more days from work by total workers compensation costs.

The information is obtained from the OSHA 300 log which does have a category for both sprains and strains and overexertion. That being said, it is at the discretion of the reporters (ie. Companies) to decide which category they use to classify an injury. For instance, if someone is exerting force by pushing a cart, and they get a shoulder strain, they may enter that injury as a sprain/strain or due to overexertion. In a way the Liberty Mutual WSI is comparing apples and oranges because one is the “root cause” (overexertion) and the other is the type of injury (sprain/strain). Therefore, this data is only as accurate as those who are reporting it and it’s difficult as a reporter to ensure you’re choosing the right category.

What is the NIOSH SLI?

The National Institute of Occupational Safety and Health has recently released an article on a Lifting Index called the Sequential Lifting Index. The intent is to use this type of LI to assess jobs in which a worker moves between workstations where the characteristics vary between the elements.  For instance, moving between entirely different workstations and lifting varying loads for various durations and frequencies.  But not only that, the SLI investigate the order in which the worker carries out the tasks and the impact that can have.

There is an article that will provide additional information if this is something that you feel your company would benefit from using. However, if the tasks are relatively similar, I would recommend using the worst case scenario or the cumulative lifting index (CLI). It may not be worth the effort to calculate the SLI if the tasks are similar.

You can find the article by clicking here.

Who were the participants in the NIOSH LE studies and the Liberty Mutual studies to come up with this data?

First of all, these studies have been expanding over the years and more and more data keeps getting entered to ensure the most accurate information is being used so the populations considered have been getting better and more representative of who is actually performing these types of tasks.

Initially, the studies started, as most studies do, with student participants who are readily available on campus. Since those initial data collections in the 80’s, the researchers have expanded their participant pool to include industrial workers. In order to get ethics approval, the participants must be considered “healthy” and “working age”. Therefore, the range will be anywhere from 25 to 45 year olds, but the population studied would not be representative of the “aging population”. If you have an older workforce, my suggestion  would be to consider designing for 90% of females as opposed to 75% of females to be more conservative with your guidelines and accommodate more individuals.


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Posted by Kent Hatcher on June 11th, 2010

Are you a Whack-A-Mole-Management Expert?

Mole Think about the responsibilities of Health and Safety Manager/Technician/Team in an ergonomics process. Its typically answering the call of the people on the shop floor about an issue or following up during an injury investigation. Classic "Whack-a-Mole-Management"!

Douglas Ross writes in a recent blog post "Whack-a-mole is a popular carnival game in which you try to hit moles that pop up randomly on a board using a rubber mallet. Every time you hit a mole, you get a point. The objective is to get enough points to qualify for a prize. Its fun and people experience a high as pent-up energy is released by whacking the moles. The challenge of not knowing where the next mole is coming from adds to the excitement. Business whack-a-mole management is based on the same principles. The challenges are the ‘moles’. As each challenge presents itself to managers, they hit it hard and fast with the hammer of position and conventional wisdom. Slam! They get one. Slam! They get another one. It requires lightning-quick decision making in a fast moving game called ‘survival of the fittest’. It’s exhausting, but it’s also fun. Each night the players go home, knowing their job remains intact because they have successfully ‘whacked’ enough organizational problems to stay for another day."

Mr. Ross calls it excitement and H&S people may call it job security, but the financial people call it cost. Whack_a_mole Does it have to be this way, does H&S have to continually fight these fires (ok, moles), new product after new product? If the Health and Safety managers funneled these issues back to engineering and were involved in best practice sharing upstream, companies (YOUR Company) would begin to eliminate the engineering issues that result in ergonomic injuries.

It’s up to you. Continue to whack the moles or start whacking your engineers and get involved early so they stop creating work environments that cause undo job stress and increased cost!


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Posted by Kent Hatcher on June 20th, 2008

Hazardous design, silver bullets, and big bears…Oh My!

Last month, Shaun Sayers of the capable blog asked a question:

Do you have a "safe system of work or (are you) hazardous by design?"

Dangerrunway_2  What spurred his thought was some whistle blower activity that suggests the volume of air traffic at London Heathrow is such that they are trying to land planes as close together as legally possible. He goes on to ponder that if a key to health and safety is to reduce risk, wouldn’t you want to create a system that allowed planes to land as far apart as possible with the same volume?

That leads us to an article in yesterday’s New York Times. David Pogue debates a solution to our own air traffic mess, the proposed ADS-B air traffic control system (dubbed NextGen) scheduled to be introduced in 2020. In the article, David quotes one of his readers (succinctly):

"David: I read your article on ADSB with great interest, as I have been an air-traffic controller for nearly 30 years. But please: before you encourage the spending of $20 billion, ask the F.A.A. to let you go to the Newark or LaGuardia towers any weekday from 3-6 p.m. You will quickly discover that providing more space in the air is not what is needed: it’s concrete.

New York, Chicago, LA…they all need concrete. A runway can only have one airplane on it at a time. The backup is at the runways. It is very rare that aircraft have to hold in the air for any reason other than weather or airport capacity."

So, as we too often see, a Big Modern Technology Silver Bullet is thrown at a supposed problem, while the root cause is left unaddressed. No matter how many planes you can fit in the air (by the way, the three mile seperation mandated between aircraft is under a minute at 160 knots) you can only land one at a time.

What we’re talking about is The Efficiency Conundrum (Thanks to Ron from LSS Academy). Apparent Efficiency is getting more planes safely in the air. True Efficiency is getting more planes safely on the ground at their destination. Another effect of apparent efficiency is often times it is the employee (in this case the air traffic controller) that gets the blame when the "fix" doesn’t work.

Furthermore, after spending $20 billion (or some other ridiculously high number) management starts to feel confident while the real problem is still out there ready to bite!

Do you yell "BEAR!" or do you watch the carnage? Remember, you could be next!

Polar_bear_2

airstrip photo credit: dweekly


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Posted by Kent Hatcher on April 22nd, 2008

Band-Aid or Inoculate?

This morning, I got my regular email from Get to the Point (from MarketingProfs – a marketing information source) and the article got me thinking. It’s focus was a study from the Georgia Institute of Technology on how companies should respond when they receive negative online feedback.

It suggested two approaches:

BandaidInvite and Engage Strategy: "entails giving customers and employees a forum where they can air their grievances, be heard, and reach a resolution."

While this works, its reactive. Another problem with it is that you probably only hear one/tenth of the complaints.

InjectInoculation Approach: "endeavors to put in place the sorts of systems that prevent the injustices that lead to disgruntled employees and customers."                               

What does this have to do with The 30-Inch View?

It seems that most companies take the Invite and Engage Strategy when it comes to workplace injuries. So, not only are companies allowing people to get hurt, they’re missing the people that are partially hurt and don’t complain.

Hurt people = High Costs

Bad Work Designs = Hurt People, Poor Quality, Low Productivity

Wouldn’t it be better to take the Inoculation Approach and look for high risk situations before they hurt people and drain productivity? Even better, design the risk out in the first place.

Is your company treating sick patients or are you inoculating your workforce against injury?

photo credits:  zmxncbv.com,  ninjapoodles


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Posted by Kent Hatcher on April 4th, 2008

Lighting the Way to Lean

One of the main reasons that we started this blog was that it would be a central place for people with different backgrounds to meet and discuss how the workplace can be improved by concentrating on the intersection of people, work and the work environment; in other words, by taking a 30-Inch View. Last week we found Josh Kerst commenting on Lean in the field of pharmaceutical manufacturing. Today, we came across an article from late last year that has application well beyond the audience of the publication.

The article discussed an often over-looked factor when it comes to workstation design: lighting.

Josh pointed out that 85% of the information that humans gather comes through our eyes.

Poor lighting not only affects the quality of work and overall productivity, but inadequate lighting forces the worker to adopt awkward positions that may lead to back pain, eyestrain, fatigue, headaches, and other ailments.

Assembly_3

Click HERE to read more on the subject.   


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Posted by Kent Hatcher on April 2nd, 2008

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