Safety category assessment for an assembly line.

I have an assembly line project consisting of power press stations, pre/after assembling parts checking stations(measure and check if parts used are OK), functionality testing station(quality inspection), and conveyor system.

Now I have difficulty determining what safety category I have to comply with for the whole assembly line. E-Stop's, light curtains(for function testing station), and safety gates(for pressing, parts checking, and fuction testing stations) will be used in safety circuits.

According to CSA Z142-02(Code for Power Press Operation), Safety category 4 must be applied for power press. But how can I assess the risk and determine the safety catedory level for the whole assembly line?

I look forward to your valuable help and suggestions.

I guess it depends on what your using. (AB, Siemens, other) What ever brand you choose should have example circuits to that will get you started. For example light curtain manual will show you how to calculate the safe distance from danger the light curtain is placed. If you have to be Cat 4 then that will narrow your search. Most of the Cat 4 that I do is based on the Siemens safety book. It gives good examples that cover most everything. Anything not covered I would recommend getting with your local distributor. They should be able to guide you in the correct direction. I would recommend after you have the safety system designed you go through it with the customer.

There are companies that will come in ($$$$$) and look at what you have make recommendations and make sure you implement it correctly.

I don't know Canadas' Machine Safety Standards, however if this project is from scratch, I would get in writing which category the client wishes to have installed. (If in an event of an accident of any desciption you will be leaving yourself wide open)
Most plants would already have some sort of standard or safety spec operational that you could use as a guide.
If an existing machine, it must be updated to current standards.

I have in the past used Pilz PNOZmulti as the safety controller interfaced with the PLC. I am not a sales rep. but have found these to very simple to install and the software is very basic to use.
I believe that Sick and others have similar controllers. These are Cat.4 rating and either company's support would be able to bring you up to speed quite quickly.
The interfacing only indicates through the PLC to say a HMI which safety circuit or device is incorrect etc.
The intial cost may be high, however, safety...
What price do you pay!!

At the final stages of commissioning the work, I get the client to re run a safety audit or similar, to ensure that all is correct.
Hope this helps

Hello hjcl;

In normal practice, the determination and implementation of the safety category of a process or machine follows the risk assessment procedure. Someone (you, if you can get paid to do it, or the client) must do a thorough examination of the different risks that personnel can be in contact with while working on the different cycles of a machine. Risk level may be reduced using guards and access limitors (for examples)in some cases; but these are simply responses to a ris=k assessment procedure. After the risk assessment has been done (and agreed upon) you can seklecty mechanisms to implement the selected risk category.

Here is a recent thread on this subject; I have posted some basic documents that may help you understand the mechanism of risk assessment.

http://www.plctalk.net/qanda/showthread.php?t=26863&highlight=Risk+assessment
Hope this helps,
Daniel Chartier

You may want to look at Siemens ASISafe or PROFISafe.

We have just started using asisafe and its excellent, Cat4 and can be zoned and you only need basically a 2 core ASI Cable run around the machine/s.

Brochure here

Your entire line does not need to be in the same category.
Whether it is easier to set it up with the same category throughout, or have different sections on different categories is something that you will have to determine.
I will post a bit more later.

Thanks for the replies, guys.

I may not apply CAT 4 to the whole production line. By dividing the line into a few sections, it may be easier to assess the risk and determine the safety category level.

I am going to contact the people who will be hired to do PHSR and ESA inspection for the machine to get more information.

Thanks to you all.

HJ

If you have the freedom to choose your components then give your local NCC Electronics guy a call. They have offered to design my safety circuits in the past if we buy their hardware. They sell Jokab products. It's worth a shot if you're stuck.

Rob

This is a complicated process and therefore a complicated task and challenge for safety. I know I have 20 years experience as safety and industrial hygiene guy. Let me see if I can make this a bit simpler and take advantage of what others have already said.

1. Evaluate each station for the various processes / procedures - ie the presses will they always punch and punch just one size hole and will it always be on the same part or are you really going to get complicated and real world by the way and do multiple tasks punch bend form etc etc on different parts etc.
2 OK now you got a what we are going to do list
3 from that list evaluate the process and employee exposure (E)the risk of an accident (R) and the cost of an accident (C). If E x R x C come up to a very high number you better do something and ensure you have adequate safeguards. Where I work (not in safety thankfully just a mechanic) company did not do 1 or 2 and lady sawed off a hand. Drs put it back on and she is going to almost fully regain function.

So the idea is to provide safeguards appropriate to the machine process and sometimes the operator (ie American Disability Act). Like others have said you may need hi level for the punches (level 4) but you do not need this protection for an inspection station where (I assume) there are no mechanical processes.

Keep it simple as possible. A well designed guard can eliminate a lot of complicated controls and expensive stuff like light curtains.

Dan Bentler