Equipment safety is no small matter. A safety door switch (safety interlock) monitors the machine guard door: if the door is not closed, the machine must not start or must stop. It is an essential part of the safety circuit and a key inspection/acceptance item.
1. Why a Safety Door Switch Is Mandatory
- Protects operators: prevents injury from spindles, tools and moving parts while the guard door is open;
- Compliance: machine exports and domestic acceptance generally follow relevant machinery safety standards (e.g. GB/T 15706 "Safety of machinery — General principles for design", GB 5226.1 "Electrical safety of machinery"), where door interlocking is a basic configuration;
- Insurance & liability: in the event of an accident, compliant safety devices clarify responsibility.
2. Selection Essentials
- Contact type: choose NC/NO contact combinations per the safety circuit design; safety circuits usually use dual-channel redundancy;
- Protection rating: in oily/dusty workshops, choose IP65 or higher;
- Mounting: confirm mounting holes, travel and door structure match (hinged doors vs sliding doors differ);
- Certification: prefer products that meet machinery safety standards and carry relevant certification;
- Interlock mode: decide whether electromagnetic locking (e.g. forced door lock during machining) is needed.
3. Common Mistakes
- ❌ Replacing a safety door switch with a regular limit switch — ordinary switches do not meet safety redundancy and tamper-proofing requirements;
- ❌ Fitting a contact but not wiring it into the safety circuit — it must connect to the PLC/safety relay circuit to actually protect;
- ❌ Continuing to use a failed door lock — replace the switch immediately when damaged; never short-circuit or bypass it.
4. KOSEND Safety Door Switches
KOSEND supplies machine safety door switches that pair with encoders and electronic handwheels, with selection guidance available. For safety solutions, call 400-100-6802 — we'll match compliant, reliable products.