What are the main breakthroughs in the industrial field for saving time in tightening processes?

Optimizing customers’ manufacturing processes is a vision that has always steered Fiam. Our Research and Development team is consistently engaged in innovating solutions with a view to boosting tightening process efficiency, optimizing the incidence of the labour cost and improving manufacturing process throughout times, achieving increasingly high levels on the workplace safety and ergonomics front.

Thanks to our experience, we’ve managed to help various companies save time in their tightening processes. Today, we wanted to tell you about the specific case of a leading company in the bicycle accessory manufacturing business.

Critical aspects encountered in the tightening process 

Our customer needed to find a solution to certain critical aspects within their tightening process. The situation before the change brought about by our tightening systems was as follows:

• Handling of over 6.5 millions screws a year
• Over 30 different screw codes
• Two workers employed full time for each assembly line/bench every day
• High number of tightenings, all performed using manual screwdrivers
• Tools used not ergonomically designed and use of manual picking systems

The main critical aspects encountered on analysing the processes included:

• plastic jigs designed for manual tightening systems
• complex product centring and orientation
• tolerances and variability typical of chemical and moulding processes employed in making the parts to be fastened

In addition to these technical aspects, there was the need to:

• ensure parts were of an aesthetically high standard, thus improving the accuracy of assembly and tightening
• address/change/overcome the workforce’s reluctance to change

In addition, automatic screwdrivers had always been considered too expensive. So, what were the factors that led the company to review its tightening processes?

Time-saving solutions for streamlined tightening processes

The company wanted its production systems to be more effective. They needed to optimize the stations required, reduce the number of manual screwdrivers and relevant maintenance costs, simplify screw handling and improve the tightening operations’ ergonomics.

What are the main advantages of a tightening system with automatic screw feeding?

First of all, eliminating the manual picking up and positioning of the screw on the screwdriver; secondly, automatically shooting the screw, which is conveyed and positioned immediately on the tightening point, ready to be tightened. All the operator has to do is pull the start lever to tighten and have a new screw being fed.

Hence the greatest benefits lie in eliminating all those tasks that do not add value (adding up to 4.80 seconds per part) and in saving a considerable amount of time for each part produced.

What have been the resulting benefits for the company opting to go with this solution?

• Much shorter tightening times: – 32% (4.80 sec. per part)
• Restored efficiency and a 25% increase in productivity
• More rational use of workers employed and tightening stations
• Implementation of two new tightening stations
• Less fatigue and screw handling
• INVESTMENT PAYBACK: in 98 days (based on a production rate of 2000 parts per day)

Find out more about our EasyDriver CA semiautomatic tightening systems.

How many inconveniences are the result of inadvertent errors during production processes in your company? What impact do they have on your productivity? On Japan’s assembly lines, these mistakes are known as “poka” and are the most common cause of rejects. “Yoke” instead comes from the verb Yokeru and means to avoid. Poka Yoke systems help the operator perform their job properly.

Let’s take a look at some practical tips for avoiding inadvertent errors with the aid of Fiam solutions. Poka Yoke devices are tools designed to identify and correct inadvertent errors as they occur. These tools are useful, for instance, on assembly lines to avoid incorrect positioning or to detect parts that might be missing from the items being produced.

Minimizing rejects with Lean Manufacturing

The basic principle lies in identifying and stopping a defect before it turns into an unusable reject. This preventive approach to tackling reject issues is at the basis of the so-called Lean Manufacturing process, the brainchild of engineer Shigeo Shingo, who studied the famous Toyota Production System.

The purpose of Poka Yoke systems, therefore, is to reduce manufacturing defects to zero, making it impossible to make mistakes during the production process and creating systems that are capable of identifying and correcting anomalies automatically.

What are the five principles of Lean Manufacturing?

• Identify Value for the Customer
• Map the Value Stream and work on eliminating activities that do not generate value
• Make Value-creating activities Flow so that they follow on from each other smoothly
• Make sure the Value Stream is pulled by the Customer
• Pursue perfection through continuous improvement

Lean Manufacturing and Poka Yoke Systems: Fiam’s answer

Based on Lean Manufacturing principles, Fiam has come up with various devices in line with the Poka Yoke concepts.

Let’s find out more about their main advantages:

• They put the production line on hold to stop the reject reaching the end and hence generating the unnecessary expense of manufacturing rejects
• They allow the mistake to be corrected and solved without delay
• They relieve operators of the need to continuously attend the machine while it is operating, meaning they are free to monitor the process as a whole, which has huge benefits in terms of end product quality
• They eliminate post-process control costs as mistakes are prevented and detected in-process

For more in-depth information, visit our page here.

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Anyone who has ever used screwdrivers on an assembly line knows how important it is to employ ergonomically designed tools, which are key to operator health and safety in the workplace: such conditions are also necessary to reduce rejects and production downtime, as well as improve the quality standard of the finished product.  In this article, we’ll be explaining how to reduce the risk of hand-arm vibration and reaction.

Vibration and reaction are risk factors still found in many manufacturing environments and our various customers – for whom operator health is a primary concern – have contacted us on a number of occasions to ask for exhaustive information on how to deal with these risk factors. Let’s find out more.

What causes the risk of hand-arm vibration?

Like most hand-held equipment, screwdrivers are a source of vibration. The definition of “Hand-arm vibration” (according to Italian legislation – D.Lgs 81/2008 – pay attention, this law refers to European legislation) is as follows: mechanical vibration that, when transmitted into an individual’s hands and arms, can lead to a health and safety risk for workers, especially vascular, osteoarticular, neurological and/or muscular disorders. This class of risk is often referred to by its acronym, HAV.

The most common effects of exposure to vibrations for the hand-arm system can be attributed to vascular or neurological lesions that result in the progressive loss of sensitivity in one of more fingers.

Solutions to hand-arm vibration risk

To reduce the risk of hand-arm vibrations, you can opt for screwdrivers with automatic air or power shut-off, which have vibration levels of less than 2,5 m/s², which is the limit established by Italian law (D.Lgs 81/2008, art. 201).

How do they work? These screwdrivers shut off the supply air to the air motor or, in the case of electric tools, shut-off the electric feed, when they reach a preset torque.

It’s worth remembering that the use of a technologically cutting-edge automatic shutoff clutch can reduce vibration levels to well below 1 m/s² under certain conditions: we should point out that, in addition to reducing the source of vibrations, exposure time is also much lower, roughly four times less, for example, than exposure time with slip clutch screwdrivers.

For more in-depth information on these technical subjects, which are linked to current regulations, take a look at our Manual on ergonomics and safety in industrial tightening operations (available in Italian).

What causes the risk of hand-arm reaction?

When a screwdriver has completed tightening and the preset torque is reached, the tool can react, with reactions that are especially evident when tightening torques are high. These reactions can cause reaction, which strains the operator’s hand and arm, causing damage to their muscles and tendons in the long term. This sort of reaction often results in sudden movements of the hand-arm system and excessive use of force needed by the operator to counter the reaction.

How can all this be prevented?

Solutions to hand-arm reaction risk

In addition to using the mechanical clutch screwdrivers with automatic shut-off as recommended above – which, by instantly cutting off transmission between the blade and rotating parts, cancel out the inertial force – when dealing with high torques and wanting to further reduce the operator’s risk of hand-arm damage, using auxiliary grips is the most effective option to prevent reaction: one of the most commonly encountered risk factors.

In such cases, you can make use of a Fiam aid devised in response to ISO standard 11148-6 that – for jobs with a torque in excess of 4 Nm for straight tools and 10 Nm for pistol tools – recommends the use of an auxiliary grip designed to reduce the reaction, sharing the load between both hands instead of just one.

Beyond auxiliary grips: short guide to other aids for hand-arm system health

We’ll now take a quick look at the main features of other ergonomic solutions that – when used in conjunction with hand-held tools – benefit operators greatly as they perform assembly jobs.

Telescopic arms They cancel out the reaction on the hand fully and ensure easy handling and unrestricted action as they:

• Absorb the tool’s reaction
• Allow the tool to rotate around its own axis and hence work correctly even with tightening jobs on an angle

Cartesian arms Solutions that:

• Stop the tool kicking back against the operator’s hand
• Require no effort to hold the tool
• Drastically reduce vibrations or eliminate them altogether
• Allow the operator to hold the tool practically straight on to the point being worked on

Do you want to receive further information on these solutions for your business? You can contact the Fiam Technical Consultancy Service directly, leaving a comment below or using the relevant contact form on our website.

In addition, you can order a copy of the “Ergonomics and safety in industrial tightening operations” manual published by Fiam and available in Italian or attend one of the numerous courses on the subject of ergonomics that we organize on a regular basis both at our premises and directly at the customers’ manufacturing plants.

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