Paul Hillam, area export manager of SafanDarley takes a look at the significant safety and ergonomic developments in press brakes.
Sheet metalworking is a global activity with many companies operating in multiple countries worldwide. These companies, including those manufacturing in Asia, are standardising their global processes which include the harmonisation of safety standards and working practices.
Safety and ergonomics are inextricably linked in this respect.
In this article, we will look at some of the significant safety and ergonomic developments applied to press brakes. The use of press brakes is still a predominantly manual operation and global manufacturers are applying their safety and ergonomic principles even in developing markets and those where compulsory safety regulations do not apply.
A major safety issue in Asia is that generally it is not a legal requirement for press brakes to be fitted with light guards. However, some machinery manufacturers are being inventive and have integrated light guard systems into the machines’ control. This enables the light guard operation to be ‘programmed’, which can result in productivity benefits.
The primary function of a light guard is to inform the machine when an operator is in the danger zone. It is therefore evident that the machine can also know when the operator is out of the danger zone and use this information intelligently.
An integrated light guard system can actually increase productivity by acting as a switch to ensure the machine is always ahead of the operator while maintaining a safe operating environment.
This programmable light curtain allows the upper beam and back gauge to move to the next step without using the foot pedal, freeing the operator to concentrate on handling the sheet.
In addition, the servo driven belt and pulley press brakes fitted with programmable light guards can carry out the bending of simple components without the operator even touching the foot pedal while maintaining the highest standards of operator safety.
Using the light guard as a switch means less fatigue for the operator, better productivity and less likelihood of accidents. These features alone can deliver significant reductions in cycle times and justifies the purchase of light guards for their productivity advantages and positive ‘side effect’ of improving operator safety.
Many press brake operations carried out in the Asian markets are on small parts with high volume. These often lend themselves to smaller machines and seated operators. As a result, there has been an increase in the number of small machines on the market. It is however important for these machines to be ergonomically sound.
The higher specification ‘ergonomic’ machines are ideal for seated operation when manufacturing smaller components. However, they retain the benefits of the standard press brakes with large beam opening, long stroke and full back gauge capacity.
They can be operated seated or standing, ensuring the operator has the most comfortable and most productive position at all times. These machines have adjustable tables, seats and control panels, all contributing to an ergonomically sound system with operator safety and comfort at the centre but with the resultant productivity benefits as well.
Side tables can be fully or partially collapsed, enabling the operator to bend components while standing. This allows the machine to be used for larger sheet metal work as you would a ‘regular’ machine.
Ergonomics does not just apply to the physical attributes of a machine. The machine control can also be enhanced. The latest touch screen controls can be customised to suit individual operators.
For example, operators can have individual password access to the machine control. The system administrator can assign various levels of authority to each operator, ensuring they only have access to functions they are trained for and have authorisation to use.
On logging in for example, the control will revert to that operator’s preferred language, icons will be displayed for left hand or right hand operation and the control will take up the desired height position.
The most sophisticated systems are so ergonomically designed that only those icons which are relevant are displayed at any one time and even the position of the icons are such that they are in the most practical position.
Some manufacturers offer machines with dual screens on the control. The dual screens are a useful option for companies wanting to have a paperless workshop as they give operators access to additional information at the machine. This gives operators the ability to access many types of additional information without having to switch from the control screen.
The additional screen can be used for the following:
- To view files in DWG, DXF, PDF, JPG, PNG, BMP, WMV format, which are coupled to current bending projects.
- To display custom applications like ERP, time management etc.
- To create a paperless environment and prevent loss of information, which reduces errors by ensuring operators have all the information necessary. For example, it is even possible to view video on a second screen which can show less skilled operators how to best handle complex and awkward products.
Sub-contracting companies are being asked to produce smaller batch sizes leading to more set ups per day, therefore anything that can reduce set up times is an advantage.
As a result, the major area to address here is tool set up. There is an abundance of ‘Quick Clamping’ systems available but one stands out above the others as it not only addresses the time issue, but also improves safety and reduces operator fatigue.
The Wila clamping system, which can be fitted to most press brake brands, can reduce set up times by up to 70 percent. The tools are mounted onto the machine vertically (not from the side) and safety clicks in each tool means that the operator can release the tool once it has been located in the top beam, leaving them free to lock the clamps.
In the hydraulic clamping version, all tools are clamped or released by the press of a single button. In addition, the machine will not commence a bend until a safe clamping pressure is reached. This cannot be said for manual clamping systems, which can lead to accidents, tool damage and loss of production.
This version of tool clamping can be further enhanced with a system called smart tool locator. This system of LED lights linked into the machine control can inform the operators where to place tools during the set up process. During the bending process, it illuminates the position where each bend is to take place.
This tooling system generally uses a tool length of 515 mm, which not only allows them to be manufactured to a higher accuracy than the old fashioned 835 mm system, but also means that the weight of the tools is much more manageable for the operator.
Right First Time
Increasing production demands and material costs mean that operators are constantly under pressure to get the product ‘Right First time’.
Usually the problems such as variations in material thickness and tensile strength are beyond the operators’ control. All batches of material vary in thickness and even the best machines can only work with the information provided. Therefore, if a machine is told the material is 1.0 mm and it is actually anywhere between 0.9 – 1.1 mm, the end result will also vary.
Automatic sheet thickness measurement systems address this issue in a very quick way and can be used on all material types. The operator sets the thickness tolerance, which is acceptable in the machine control.
The sheet is presented to the device, which is adjacent to the back gauge fingers and it automatically measures the material thickness. If it is within thickness tolerance, the control will automatically adjust the program and pinch point for the ‘actual’ thickness rather than the theoretical thickness, resulting in a more accurate result. If the material is outside the set tolerance, the machine will not bend, thereby reducing scrap and improving productivity. The whole process takes just a couple of seconds.
When the tensile strength and spring back is also a problem, then a laser angle measurement system could be the solution. These systems automatically measure and correct angles during the bending process, ensuring every component is ‘Right First Time’.
When handling larger components, which require a high level of accuracy, then it is beneficial not to have to make corrections to bends that would require additional handling of awkward, large and heavy products, which is both a safety issue and causes the operator to tire more quickly.
In order to help operators, two laser sensors are mounted on either side of the machine table and are CNC controlled. The system continuously monitors and corrects the position of the Y-axis based on the required product angle and therefore guarantees an end product of the highest angle precision. The system automatically adjusts the crowning and at the same time, takes into account the spring back.
Both of these systems (Sheet Thickness & Laser Angle Measurement) improve quality and dramatically reduce handling and fatigue of the operator.
For many products, it is not the actual bending process which is a problem but more the ‘handling’ of the material pre and post bending.
Handling can pose significant safety issues and place unnecessary strain on the operators. In addition, awkward and/or heavy products, if handled badly, can also give quality problems. For this reason, manufacturers are offering a range of handling and bending aids, some of which are CNC controlled.
Each type of product poses different problems. For example, very thin materials can be so flexible that they need greater support than a mere individual operator can provide. For heavier components, the physical weight can make it impossible for manual operation and so, a range of weight capacities is available.
‘Bending aids’ differ from sheet supports in that they follow and support the component during the actual bending process. CNC bending aids can be programmed to follow the component during bending, even pausing to allow for the compression of the material where heavy bending force has been applied. The speed of the aids is synchronised with the bending process and is programmable to a speed that matches the operator’s capabilities. Some bending aids can even be detached and shared with other machines.
Google is the highest profile user of this technology for navigation. In the sheet metal industry, SafanDarley demonstrated a concept version of augmented reality for press brake operation at the Euroblech exhibition in 2012, where it won the Innovation award.
For press brakes, the main areas of benefit are projections onto the machine and by projecting information onto the operators’ glasses. This would be similar to projecting satellite navigation information onto the windshield of a car.
With the help of projections onto the operators’ glasses, they will be able to perform better. These glasses can show additional information just beneath the field of view of the operators, so that they do not need to move their head and focus on other places such as a control screen or drawing, giving them full concentration on the product during the bending process.
Typically, the following information could be projected onto the glasses:
- Position of the back gauge fingers.
- Bend sequence and component positioning information
- Notes, warnings
- Production data
- Service support
In summary, it is evident that global companies will continue to harmonise their operations. The challenge for machinery manufacturers and users is to ensure that safety and ergonomics will be at the forefront of all product development.
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