Rely on an E-stop to act as an interlock
Team,
I have been in a pretty heated conversation this past few months trying to get an upgrade for my equipment to allow the use of a two-circuit safety system.
I was told no upgrade and to figure out how to guard it in the next month or their are shutting that assesst down and moving it out of my site. It is the only equipment keeping us afloat at the moment.
My most senior individual wants to tie in a rely to the local E-stop to creat an interlock situation. How ever, becuase I am an analog system with no 2 ciruit system it can not be tested or monitored. How can I correctly word this to my senior leadership that this is still not the correct way to handle this.
Thanks,
John
Comments (11)
Just want to make sure I'm understanding the situation correctly - what type of equipment is it and what are you wanting to do with the E-stop/interlock?
John:
I HATE ROLLERS!!!!!
I was at a customer at the end of February. As we toured the facility we saw the typical things we often see, unregulated air lines, bench grinders with no tongue guards and bench rests >1/4" (I know <1/8") from the wheels, poor housekeeping. power strips and extension cords all over, and a Maint. Shop that was a Gold Mine of hazards! It was a Ag Services company that provides mechanical work to farmers and also builds Ag sprayers. We walked over to a another building that was there Fab and Machine Shop. The first thing I saw was a 10' brake press and next to it was a set of three hardened steel rollers with each roller being about 10" in OD. The rollers were 12' long! Neither the brake press or the rollers had any guarding! (the brake press had a set of two hand controls that were deactivated and pushed off to the side). I will save the brake press for another time.
The rollers were very dusty and obviously were not used often. I asked what it was used for and the tour guide told me to flatten coiled sheet metal before bending. He told me they only used the machine a few times a year. I suggested to him they lock the machine out or fully disconnect the power until it was needed. In my report to the owner I suggested that they get rid of the machine and just purchase the sheet metal already flattened and not from coils the few times they needed it. There would be an increased cost for the sheet metal but the cost to guard the machine would be north of $40K. Light curtains may work but lasers would be better, thus the cost. I had not yet considered the control system of this older machine so it could be much more! To their credit they locked out the machine and sold it last week.
Are you talking a 2 circuit system for guarding (PSDI), lockout, or both?
Update: I think we have found a way to have a guard that is manipulated by the machine movement itself to lower a guard into place when the rolls are closed for running.
John:
I just got an email on this. I have not read in detail but it might help you. I briefly see it even talks about e-Stops.
Fitz
https://automation.omron.com/en/us/solutions/white-papers/understanding-machine-safety-risk-assessment?utm_campaign=US-OEI-White-Paper&utm_medium=email&_hsenc=p2ANqtz--nW_OIdz_cJdj9cKw0ehc_auFr7w2NzfqJ64qM5xyzP2tdDny0tzMvVkAc4jqOSvhtWxsMYqGeda_wyRMe-oKUeamNxA&_hsmi=302420601&utm_content=302420601&utm_source=hs_email