Saftey Door Switches

[Scottjit]

Does anyone know what Osha rule is on Door switches for CNC mills and lathes. The machines are old (1997) to new (2009). Some have them that do not work and others did not come with them. Does the door switch need to stop all movement, spindle and axis, or just single block the program? Some of the machine have set up keys and others don't. I think I will need to rewrite the ladder in some of the old machines to install a door switch. Any information would be great.

[underthetire]

I know way to well. Fast and simple is if it came with it, it has to be functioning the same as when it left the factory. If you start changing the door locks system, you will need to meet the 2010 spec, so basically you cant run the spindle with the door open at all. The biggest problem have been the taiwan/China machines. If they were available from the factory, whether your machine came with it or not, it's supposed to have it. Now, larger machines are exempt from door locks, as well as any machine that doesn't have a automatic tool changer. There are several pages of rules in the ANSI, OSHA, and NFPA about it. EC has there own. It's a long road to go down.

[Al_The_Man]

I have had to fit safety switches and light curtains etc for some companies, usually due to a strong union presence that insist on management upgrading machine safety.
With a CNC machine you have to stop both axis and spindle movement, apart from the safety aspect, if you just stopped the spindle it would result in a tool crash for sure.
I usually have fitted safety switches these are special switches for this application, they usually come red in colour and have a switch operator that requires the sequence be correct, this avoids anyone jimmying an over ride.
The machine program stop can be interlocked with the switches and also prevents a restart.
Also most CNC's allow operator messages, and I include one just to advise the operator the reason for the stoppage.
Al.

[Scottjit]

Where can I find the Osha regulations?

[underthetire]

I'll see if I can get a copy, the problem is even in the Osha says see ASZI XXX standards. So you really need both.

[Al_The_Man]

You probably want to start with ANSI/NFPA79, as I would hazard a guess that OSHA base alot of there rulings on what it contains.
Many times it is of a fairly vague nature, for e.g.

"6.5 Safeguarding against Other Hazards.
Where hazards are identified for the specific machine........... provisions for the connection of appropriate safeguards (e.g. guards and protective devices) shall be made.
These safeguards shall function in accordance with the requirements of the specific machine."

IOW, each machine is evaluated according to its particular function.
Al.

[Wizzard of H]

For those looking for the documentation, most of the USA stuff is on the web at: "http://63.234.227.130/pls/oshaweb/owastand.display_standard_group?p_toc_level=1&p_part_number=1910"
Or look up US Department of Labour OSHA 19210.

For Europe, all of the requirements are in the Machinery Directive at:
Machinery - European standards - Enterprise and Industry

Be careful, in the US and in Europe, standards are written by private organizations and are rarely considered mandatory. In addition to this, the copy of the standards are sold to you by companies making money doing so. The US OSHA and EU Machinery Directive conversely are free of charge as they are laws.

[DouglasR]

For years it was a helter skelter mish mosh of rules. My 1983 Okuma LB15 has a door interlock system with a key override for single block operation. My 1986 Mori SL3-H does not have one. Go figure.

I nearly bought a brand new Mori and it had a door interlock with key for single block/slow rapid.

[Wizzard of H]

A little more clarification...
The OSHA web site can be found by searching for: OSHA.gov 1910.

And some distinctions...
In the USA, the OSHA requirements are placed on the "creator of a workplace". That is the person who hires workers. It is not a requirement on how machines must be designed and built. It is only a requirement on how they must be installed and used in a workplace (i.e. worker safety).

In Europe, the Machinery Directive is the only applicable law and it IS a requirement on the design and construction of machines. So manufacturers of machines must comply with it.