“Assistive Device for Calendar Production”




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Team 27

Literature Review


“Assistive Device for Calendar Production”


Bryan Whitney Belt

Lisa Furby

Eric Hoffmann

Ronnie Mays Jr.

Samir Shah


TABLE OF CONTENTS


Introduction……………………………………………………………………………………………..1


Ergonomics………………………………………………………………………………………………4


Stapler Mechanism…………………………………………………………………………………..6


Mechanical Advantage …………………………………………………………………………….9


Jigs and Fixtures……………………………………………………………………………………….13


References……………………………………………………………………………………………….16


LIST OF TABLES & FIGURES


Figure 1: Standard Stapler Diagram………………………………………………………….6


Figure 2: Standard Chisel Staple Diagram………………………………………………….7


Figure 3: Mechanical Advantage Diagram……………………………………………….10


Figure 4: Four-Bar Mechanism ………………………………………………………………..11


Figure 5 Wooden Stapler Jig……………………………………………………………………..15




Introduction

In the United States, over 18% of the population, more than 54.4 million people, have some level of disability. Of those who have a disability, roughly 35 million or 12% of the national population is considered to have a severe disability. Individuals who suffer from disabilities have reported difficulties in securing jobs and performing job duties. A census performed in 2005 reports that 22.7 million disabled individuals reported being limited in types of jobs they were able to perform, and 13.3 million of those individuals report their disabilities prevent them from working. Unemployment and compensation continue to be a problem for those who are disabled. Of those between the ages of 21 and 64, less than 50% of disabled individuals are employed. The rate of unemployment for all those who are disabled is roughly 70% as compared to the 16.5% unemployment rates for those who do not have a disability. More than 25% of severely disabled individuals are impoverished [22]. [22]

Other issues facing those with disabilities include the transition from the school system and the wait lists for government funded services. Every year, more than 90,000 disabled young adults graduate from schools once they have reached the maximum amount of time a state permits them to stay in school. Once these young adults graduate, they often have nowhere to go except a waitlist for adult programs. Without these programs, there are very limited opportunities for interaction with others, any type of employment, or self sufficiency [24]. [24]

In studies on the quality of life of disabled individuals, the subjects responded that there were negative impacts on their dignity due to dependence on others for personal care, lack of employment, loss of power at their employment, and exclusion from activities. Every subject in the study responded that employment and their economic security were extremely important to each of them. Of those who had some level of economic security, most had achieved their economic security prior to the onset of their disability. The subjects of the study felt they were under-employed, underappreciated and wanted increased pay and opportunities for job advancement. The subjects felt they could increase their pay but did notn’t know how to, and that often adaptive equipment and technology were not implemented to enhance their employment capabilities. Many with disabilities said that with appropriate support services they were able to be more self-dependent and active in their communities allowing them to feel better about themselves. The study found that disability impacted every aspect of the person’s life, and many subjects associated their disability with a perceived decrease in their quality of life [6]. [6]

The Ability One Challenge is a competition in which engineering students work with a person with disabilities in order to design and build a device which can assist them in their employment. The competition is sponsored by NISH, National Industries for the Severely Handicapped. NISH is a non for profit organization which focuses on increasing employment opportunities for those who are disabled. The objectives of NISH are to create, design, and re-engineer jobs for people with disabilities, increase wages and benefits for those workers, enhance advancement opportunities, and increase the number of personally satisfying employment opportunities. The Ability One Program, part of NISH, currently provides employment opportunities for more than 40,000 disabled people and is the largest single source of employment for people with severe disabilities. As part of the Ability One Program, over 600 non for profit organizations are employing the disabled individuals [11]. [11]

As part of the design process, our team is working closely with Specialized Training for Adult Rehabilitation (START). START provides sheltered employment as well as supported employment, but the clients we are working with are part of the sheltered employment. Sheltered employment programs are designed to assist individuals who are not capable of working in a competitive employment environment [15]. [15] At START, several disabled individuals can work on different types of jobs such as cutting cardboard boxes and assembling calendars. Many of the jobs which the clients perform are jobs that are outsourced by local companies.

NISH and other non for profit organizations such as START focus on increasing the number of jobs that are available to those who have disabilities, and also attempt to increase wages and advancement opportunities. These are factors which directly impact the quality of life of those with disabilities. The Ability One Challenge program looks to assist in creating more jobs or to allow an individual to perform their current job better.


Ergonomics


Ergonomics, also known as human engineering, is “an applied science that coordinates the design of devices, systems, and physical working conditions with the capacities and requirements of the worker” [5]. The device for this project must be designed for the capacities and requirements of developmentally disabled workers [17]. This makes ergonomics very important to this project.

The capacities and requirements of developmentally disabled employees are often handled through vocational evaluation [18]. This assessment generally involves a field of medicine known as occupational therapy [23]. Occupational therapy is similar to physical therapy but has a focus on helping individuals participate in everyday life or modifying an environment to allow them to participate [7]. An occupational therapist will often evaluate hand strength and other arm strength factors to determine a patient’s ability to achieve certain tasks. Developmentally disabled individuals at times fall outside of these norms. Therefore, this device must be designed to fit those needs.

The team does not have the ability or expertise to evaluate the individuals that will be using this device. So it will be heavily reliant on the evaluations of the NISH sponsor, START [17]. Their advice and feedback will be invaluable and be input into the various iterations of ergonomics for this product.

The stapling mechanism has little ability to perform therapy on individuals. So the primary goal for this device will be in modifying the environment in order to allow the employees to use the device. This will incorporate modifications to the stapler, mechanical advantage and the jig for placement of the device. The stapler must be able to pierce the paper and crimp the staple with slightly less input force than is expected from an average individual. This will require some mechanical advantage that will multiply the input force of the employee and increase their ability to handle this repetitive motion. Another consideration in this area will be handle shape due to grasp issues. The placement jig must be easily usable for those with dexterity and range of motion issues. It must also be an easily repeated motion that will allow the employee to get the place right every time. These are the primary ergonomic concerns.


Stapling Mechanism

Stapler

A stapler is a simplistic mechanism consisting mainly of a hammer, staple, and anvil as shown in Figure 1. [20]



Figure 13: Standard Stapler Diagram [14]


The hammer pushes down on the top of the staple, pressing it into the grooves in the anvil causing the staple legs to buckle which in turn locks the papers into the staple [19]. [19]As can be observed from Figure 1, the operator pushes directly on top of where the hammer presses against the staple. Most common staplers have a mechanical advantage of one. Industrial grade staplers, however, incorporate a lever which will increase the mechanical advantage, requiring the operator to input less force [14]. [14]

There is a wide variety of staplers ranging from more simplistic ones, such as Figure 1, to complex electrical and pneumatic powered staplers [20]. [20]

The most common brands of staplers are Swingline, Stanley Bostitch, and the Staples brand. There are also staple-free staplers on the market, but these can only fasten around four pages at a time, which is unsuitable for this design [3]. [3]


Staple

The other important part of the stapling mechanism is the staple. There is a wide range of commercially-used staples.



Figure 42: Standard Chisel Staple Diagram


Staples vary in the gauge of the metal used, type of metal used, length of the legs, and the shape of the teeth. Figure 2 shows a staple with chisel point teeth. This type of staple has been found, on average, to go through more paper, jam less, and require less effort than the ordinary flat tooth staple. The sharp pointed teeth of a chisel staple allow it to puncture paper with less resistance. The manufacturing of a chisel staple is more involved than a flat staple, making it more expensive, but the increase in efficencyefficiency of a chisel staple often counters the extra cost [21]. [21]


Stapling Assembly

A great deal of research goes into improving the stapler and staples. Companies are continually researching ways to make the stapler more ergonomic. Research is also being done to reduce staple jamming, and to increase the efficiency of operating and maintaining the assembly. Larger companies even go as far as having a stapler maintenance program where technicians ensure that the stapler is in proper working order [3]. [3]

Because staplers undergo a lot of “wear and tear”, they tend to deteriorate faster than other office equipment. Therefore, for this project’s design, the goal is to incorporate a stapler that can be purchased over the counter in case one of the staplers becomes faulty and needs to be either repaired or replaced. For this reason, it is important to consider that the stapler assembly can easily be accessed or removed to make downtime and repair time as quick as possible.

Other factors that need to be considered when choosing what stapler to utilize involve how the stapler will be used and what material it will be used on. Since the intended machine design will only be used to create staple calendars, we will need to staple about thirteen pages, including the vinyl backing. Most regular staplers are rated to staple about twenty pages, so this will not present a problem. The stapler will be used quite frequently, so it may be more cost effective to purchase a heavier duty stapler that will last longer.


Mechanical Advantage

The concept of mechanical advantage has been around for several years. With today’s evolving technologies, there is always continuing demand for the use of mechanical advantage. The idea of mechanical advantage involves effectively amplifying input force to your desired output of a simple machine [4]. Some common mechanical advantage devices include:

  • Gears (Bicycles/Car Transmissions)

  • Levers

  • Pulleys

  • Inclined Plane

The above devices are not gaining something from nothing. In general there is a trade off between two changeable variables in a system to keep power and work constant [16]. More specifically in the case of mechanical advantage, you must decrease a factor to increase another. The engineering explanation of mechanical advantage is the ratio of Foutput to Finput (i.e. ). In a rotational example such as a gear system, torque (τ) and angular velocity () are the factors which are often manipulated. Increasing one factor will decrease the other improving the performance of the system for a given situation [9]. However, for this design the primary focus will be on the concept of displacement (Δx) as well as force (F) and their uses. For a lever, displacement (Δx) and force (F) are the alternating factors. Figure 3 below shows the mechanical advantage of a lever system for a certain situation.




Figure 3: Mechanical Advantage Diagram


Here an increased displacement (Δx) and decreased force (F) are observed on the input side (right) which causes a decreased displacement (Δx) and increased force (F) on the output side (left) allowing for the heavy load to be lifted [12].

The project design will utilize a stapler mechanism which typically does not use much mechanical advantage. This means that the input force applied to the stapler is the same output force required to inject the staple into a medium. The force required to staple increases depending on the hardness and thickness of the medium the staple must travel through.

For the purpose of the design, the medium consists of a small calendar and a vinyl sheet with an approximate overall thickness of 1/16”. Due to the operating circumstances and the thickness of the medium, having mechanical advantage here is favorable. However, implementing a lever type system to amplify output force for the staple will be inefficient due to its ratio of size to mechanical advantage. Instead, utilizing a more compact mechanism would be more beneficial. Compact mechanisms have huge potential for gaining infinite mechanical advantage and are typically easier to design. A general type of compact mechanism is the 4-bar linkage system. The concept of a 4-bar mechanism is similar to that of the lever [12]. In today’s market there are many tools which utilize a 4-bar type linkage mechanism to increase mechanical advantage. Two common types of 4-bars are lever or toggle clamps and vice grips.

The above are defined as mechanisms because they have two or more moveable links [3]. The vice grip consists of a lever where the input force is applied. This lever is an extension of a 4-bar mechanism on the vice grip. The nature of the mechanism allows a significantly amplified output force by increasing lever displacement and decreasing jaw displacement. A typical 4-bar mechanism includes four fundamental parts [10]:

  • Crank (Input F)

  • Coupler

  • Lever

  • Frame




Figure 4: Four-Bar Mechanism


In Figure 4, links p, l, s, and q are the crank (input), coupler, lever (output), and frame respectively [5]. The system has mechanical advantage depending on the mechanism’s configuration. When designing a mechanism to suit this project’s goal involving stapling, a consideration of speed and force must be accounted for. Typical stapler effectiveness is a function of both speed and force applied.


Jigs and Fixtures

A jig can be defined as a work piece locating and holding device that will guide and control the position of a desired tool. The difference between a jig and a fixture is that fixtures do not control the actual working tool. In the case of the proposed project a stapler would be implemented as the tool, and based on the aforementioned definition the holding device would be classified as a jig because the tool would be integrated into the holding device, thus the device controls the tool. There are many factors that should be taken into consideration when designing a jig. The device must be strong enough to prevent deflection and therefore desires machining tolerances. Permanent sections of the jig should be welded together where as replaceable/disposable portions should be bolted on. A key design feature of a jig that is especially critical to our project is that a work piece in a jig should only be able to be positioned in the correct manner. This design also must allow the work piece to be inserted or removed easily. Clamps should operate rapidly and use springs to reduce user effort and to secure properly. Consideration should take into account chip removal; this would relate to the project if a staple were to get lodged in the jig and have to be removed for operation to continue [13].

Another important design consideration is the material the jig is made out of. There are three major material categories that need to be considered for the design of the jig; metal, wood and plastics. They all provide pros and cons and bring forth new design considerations. By far the most durable material that can be used is metal. It is suggested that steels with low carbon content not be used because such steels are not as easily machined to provide a smooth work surface [8]. Wood is easy to work with and is readily available however it will not provide the durability need to support the forces of repetitive stapling without additional support from alternate material. Plastics also fall into the same category as wood with durability issues. However, the use of plastic for the jig may be considered as to reduce device weight and manufacturing costs.

The tolerance of the jig will need to be very precise so that the design objective of a consistent quality product can be achieved. There are many different types of tolerances; straightness, length, position, diameter, flatness, and gap tolerance. A few that may be critical to the project include length, position and gap tolerances. The position is especially important because a staple anvil is needed for proper operation and it must be placed in a precise location to work properly.

Current Jig Technologies

A company in Tulsa, Oklahoma that resembles the START organization (providing job to people with severe disabilities), has currently implemented a stapling jig in their workforce operations. The jig is manufactured from wood and has a cut out for an automatic stapler. The worker can place the papers in the jig and it is automatically stapled in the correct locations [1]. The jig is pictured below.



Figure 5: Wooden stapler jig, Assistive Technology Solutions [1]


The plans for this particular jig were purchased from Assistive Technology Solutions. This company has set forth to provide useful assistive devices that enrich the quality of life for people with disabilities. The company takes the engineering plans of assisted technology devices and publishes fabrication and assembly plans that are purchased by needing facilities. Their website also provides a list of companies and website that produce and market disability assistive devices [2].


References


[1] "Ashley's Mom - Exploring and designing technology solutions for today's educational needs." Ashley's Mom, Inc. - Exploring and designing technology solutions for today’s educational needs. Web. 16 Oct. 2009. .

[2] Assistive Technology Solutions. Web. 16 Oct. 2009. .

[3] "Best Staplers - Stapler Reviews - Electric Stapler - Swingline vsvs. Bostitch." Galt Technology: Technology Reviews, Internet Guides, Product Reviews, Travel Guides. Web. 07 Oct. 2009. .

[4] Congress, World. Theory of Machines and Mechanisms Proceedings of the 7th World Congress, 17-22 September 1987, Sevilla, Spain. Oxford: Pergamon, 1987. Print.

[5] "Ergonomics." Random House Webster’s College Dictionary. New York, 2005. Print.

[6] Fresher-Samways, Kathleen, Susan E. Roush, Kathy Choi, Yvette Desrosiers, and George Steel. "Perceived Quality of Life of Adults with Developmental and Other Significant Disabilities." Disability and Rehabilitation 25.19 (2003): 1097-105. Ebscohost. Web. 7 Oct. 2009.

[7] Hacker, B. "Single Subject Research Strategies in Occupational Therapy." The American Journal of Occupational Therapy. Feb (1980). Print.

[8] Henriksen, Erik Karl. Jig and fixture design manual. New York: Industrial, 1973. Print.

[9] Howell, Larry L. Compliant Mechanisms. New York: Wiley-Interscience, 2001. Print.

[10] "Linkages." Web. 15 Oct. 2009. .

[11] NISH. Web. 08 Oct. 2009. .

[12] Okolischan, Raymond A. Self-adjusting toggle clamps for factory fixtures and the like. Patent 4407493. 4 Oct. 1983. Print.

[13] Pollack, Herman W. Tool design. 2nd ed. Englewood Cliffs, N.J: Prentice-Hall, 1988. Print.

[14] "The role of key characteristics in the design of mechanical assemblies." Web. 07 Oct. 2009. .

[15] Rosen, Marvin, Albert Bussone, Peter Dakunchak, and John Cramp, Jr. "Sheltered Employment and the Second Generation Workshop." Journal of Rehabilitation January/February/March (1993): 30-34. Ebscohost. Web. 08 Oct. 2009.

[16] Sclater, Neil, and Nicholas Chironis. Mechanisms and Mechanical Devices Sourcebook, Fourth Edition. New York: McGraw-Hill Professional, 2006. Print.

[17] Specialized Training for Adult Rehabilitation. Web. 17 Oct. 2009. .

[18] Specialized Training for Adult Rehabilitation. Web. 17 Oct. 2009. .

[19] "Stapler: Facts, Discussion Forum, and Encyclopedia Article." Web. 07 Oct. 2009. .

[20] "Stapler Guide - Staplers - ABC Office." Office Equipment - Paper Shredders & More. Web. 08 Oct. 2009. .

[21] "Swingline Premium Staples -- Comparing them with Standard Staples - Swingline Premium Standard Staples 25 Sheet Capacity 210 Strip Count 5000/Box - Epinions.com." Reviews from Epinions. Web. 07 Oct. 2009. .

[22] U.S. Department of Commerce. Americans With Disabilities: 2005 Household Economic Studies. U.S. CENSUS BUREAU, Dec. 2008. Web. 08 Oct. 2009. .

[23] "WFOT | World Federation of Occupational Therapists | Occupational Therapy." WFOT | World Federation Of Occupational Therapists | Occupational Therapy. Web. 17 Oct. 2009. .

[24] Zaslow, Jeffrey. "Moving On: The Graduates: What Happens After Young Disabled Adults Leave School." Wall Street Journal [New York City] 29 Dec. 2005: D1. ProQuest. Web. 08 Oct. 2009.




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