9/29/2021 11:50 AM | |
Posts: 1 Rating: (0) |
Is it necessary to have a normal Stop control (Not an Emergency Stop) on a machine such as a pneumatic press which is fully guarded off and guards monitored by non contact safety switches and safety CPU? We've developed a bench top press machine but did not see a reason to include a stop function but looking at the Directive 2006/42/EC - Annex 1 1.2.4 Stopping: 1.2.4 Stopping 1.2.4.1 Normal Stop Machinery must be fitted with a control device whereby the machinery can be brought safely to a complete stop. Each workstation must be fitted with a control device to stop some or all of the functions of the machinery, depending on the existing hazards, so that the machine is rendered safe Our press machine operate by an operator sliding in a drawer directy under the pneumatic press. Once the drawer is in position (Monitored by safety switch), the pneumatic press drops at a controlled slow rate and retracts to start position once part is pressed. We don't see a reason to have a stop button control as the hazard zone is guarded off and monitored by protective safety devices but Directive 2006/42/EC states that machinery must be fitted with a Stop control device. Can I please get advice on the matter? Thanks in advance. ------------------------------------------------------------------------------------------ |
Last edited by: Jen_Moderator at: 09/29/2021 13:37:32New subject after splitting |
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9/29/2021 3:55 PM | |
Joined: 7/7/2010 Last visit: 5/1/2024 Posts: 14661 Rating: (2350) |
Let's say for setup and testing things, your press has a manual mode. In manual mode there is the option using a two-hand safety control scheme to lower the press. If it has a "single cycle" test button which can cause even in Manual mode semi-automated motion, having a 2-hand safety setup which requires the operator to have 2 hands on these safety switches during this test cycle. Releasing either safety switch would stop the press in a "normal" manner rather than an "emergency stop" manner. For the press, moving into press position in manual mode should basically vent retract side of piston, slowly and in a controlled manner pressurize the extend side of the piston - but only while the operator is using both hands to cause the motion. For a non-Emergency Stop for motion during that movement, releasing either hand of the 2-hand operation should vent the extend side of the piston and - depending on whether it should "stop" or "retract" - pressurize retract side of piston or close off both piston vents. You might consider automated operator hand retraction assist devices that are like Parents that grab their children away from the roadside in case a vehicle is about to hit their child - if that's important for your application. With a slow controlled extend and retract even in the event of a control device failure, retraction assistance is probably not necessary. That's what your project Risk Assessment should reveal though.
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