Product category:
Machinery/plant guarding and protection
News Release from: Jokab Safety UK | Subject: Guarding systems at GPS
Edited by the Manufacturingtalk Editorial
Team on 17 April 2008
Safety system reduces costs without
compromise
Two manufacturing cells needed to be refurbished and brought up to the current safety requirements and a plastic s piping products maker asked Syscom UK to evaluate the machine guarding.
GPS is part of the world's largest manufacturer and supplier of high performance plastics piping products and fittings for the water and gas industries In 2003, GPS acquired two manufacturing cells that had to be refurbished and brought up to the current safety requirements
This article was originally published on Manufacturingtalk on 17 Aug 2004 at 8.00am (UK)
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Syscom UK was asked to evaluate the machine guarding and increase the safety integrity.
* Risk factor - when designing and building machinery, Jokab told manufac turingtalk that one had to consider the risk factor when operators are working with the machine.
This is initially started by creating a Risk Assessment.
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The Risk Assessment allows the manufacturer of the machine to consider all the possible risks and dangerous areas in the machine.
Once these have been identified, the machine builder then can develop the safety system to meet the requirements put down in the standards.
* categories - there are four categories which are used to identify the reliability of the safety system.
These are called simply 1, 2, 3 and 4.
Depending of the type of injury, exposure to the hazard and the possibility of avoiding the hazard, then one can use these parameters to work out which category level the machine needs to comply to.
Category 4 is seen to be at the highest level one can adapt to for machine safety.
Recently there have been changes to the standards the way components and systems are produced.
The new SIL levels, means that one has to consider the level of reliability, predictability and traceability of all components used within the safety system, which is related to the failure time consequence.
At GPS UK the cells had a variety of possible dangers from Category 2 to 4.
* Avoiding complex interlocking - having looked at the options it was decided that the manufacturing cells needed to be brought up to Category 4, SIL3 as it was simpler to keep the safety levels the same to prevent any unecessary complex interlocking within the safety system.
The cells consisted of a gantry robot and an injection moulding machine together with other automated processes.
The focus was to prevent operators accessing the manufacturing cell during production and to allow a full integration of all the safety devices from different areas of the cell.
Syscom UK had decided to use the Vital Solution from Jokab Safety as it met the Category 4 requirements.
Vital Solution also could also connect all the devices to one safety monitoring unit.
It meant that Syscom and GPS could see the space saving and cost reduction possibilities.
At the same time, Vital fitted in with the theme of having a centralised control system.
The safety system consisted of Emergency Stop Buttons and Jokab's JSNY9 door interlock switches.
These devices had Tina 3A interfaces installed which monitored the two normally closed contacts and changed the signal to the Vital unit, should the safety devices be operated.
Where it was not possible to use Tina 3A the Tina 7A was utilised having the same functionality.
A Spot 10 safety light beam was also in the safety circuit to monitor the gantry robot position.
In order to make the connection of all the devices simple Syscom UK added some Tina 4A connection modules, which allows all the safety devices to be taken to one point before connecting to the Vital Controller.
The manufacturing cells had been in full production, when GPS added a third cell.
Again Jokab Safety's Vital system was specified and installed.
* Different automation systems - during 2007 Syscom designed a new manufacturing cell and the automation systems were different to that of the previous cells.
Jokab Safety were asked to look at the machine safety possibilities.
The interlocking and reset requirements in the new cell were more complex than the previous systems and in order to meet these requirements, Pluto safety PLC was the best solution.
Pluto was able to allow Syscom to still use the Tina interfaces, as used in the Vital solution, as Pluto can utilise three dynamic pulse outputs.
In other words, said Jokab, it could be seen to have three Vital units inbuilt.
The main benefit is that Pluto is a fully programmable PLC system, therefore any interlocking for the failsafe outputs or complex reset requirements could be handled easily.
Pluto also offers the flexibility of making changes to the safety system without any major wiring changes in the control panel.
GPS and Syscom UK said that they have been very satisfied with the quality and product support from Jokab Safety and are currently investigating other possibilities for future projects.
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