DX-D2 / DX-D3 Guard Door Interlock Switches
Tongue-operated, positive-break interlocks that tell your safety relay the guard is really closed — the straightforward, million-cycle way to monitor doors that do not need to be locked shut.
- Positive-break NC contacts: ≥60 N / ≥10 mm forced separation
- 4 contact codes, from 1NC+1NO up to 3NC
- IP67 resin head; 1,000,000-cycle mechanical life
- 8 key insertion directions, DX-K actuator range
- Designed to IEC/EN 60947-5-1 and GB 14048.5-2017
The Monitoring Tier of the DX Door-Lock Family
Not every guard needs to be locked. On many machine tools, packaging cells and test rigs the hazard stops as fast as the door can physically be opened — what the circuit needs is a trustworthy door-closed signal, not a holding force. The DX-D2 and DX-D3 deliver exactly that: a stainless actuator key on the door enters the switch head, and withdrawing it mechanically forces the NC contacts open.
Because they omit the solenoid and lock segment of their DX-W siblings, these switches are the economical entry point of the DX range — and often the correct engineering choice, since ISO risk-assessment logic penalises unnecessary complexity. When a later assessment does demand locking, the mounting concept stays in the family: move up to the DX-W2/DX-W3 solenoid locks, the RFID-monitored DX-D6, or bolt the existing DX-D2/D3 onto a DXL door bolt.
The D2 and D3 bodies share the same operating principle and IP67 resin head; the published difference is contact capacity — DX-D2 carries two contacts (CO or 2C), DX-D3 carries three (2CO or 3C).
Positive-Break Operation, Illustrated
Original schematic, simplified — internal cam geometry is representative only.
Technical Specifications
| Operating principle | Tongue/key-operated mechanical contacts (no locking segment) |
|---|---|
| Contact configurations | DX-D2-CO (1NC+1NO) / DX-D2-2C (2NC) / DX-D3-2CO (2NC+1NO) / DX-D3-3C (3NC) |
| Forced separation | ≥60 N over ≥10 mm of travel (positive break) |
| Rated insulation voltage Ui | 400 V |
| Conventional thermal current Ith | 8 A |
| Rated operating point Ue / Ie | AC 400 V / 2 A |
| Mechanical / electrical life | 1,000,000 / 300,000 operations |
| Head material & protection | Resin head, IP67 |
| Key insertion | 8 directions; DX-K series actuator keys (preparation clearance 1-2.5 mm, slot tolerance ±1 mm) |
| Cable connection | Factory-fitted PG13.5 cable gland |
| Standards basis | Designed to IEC/EN 60947-5-1 and GB 14048.5-2017 (design and test reference standards); certification documents on request |
Choosing Between the Four Codes
| Ordering code | Contacts | Safety channels | Status contact | Best for |
|---|---|---|---|---|
| DX-D2-CO | 1NC + 1NO | 1 | Yes | Basic interlock + door lamp/PLC bit |
| DX-D2-2C | 2NC | 2 | No | Dual-channel circuit into DQSRN / DA31 |
| DX-D3-2CO | 2NC + 1NO | 2 | Yes | Dual channel plus status feedback |
| DX-D3-3C | 3NC | 3 | No | Three loops / spare NC channel |
DX-D2-2C Variant
Series Features
Typical Applications
Machine-Tool Guard Doors
Confirm the enclosure door is shut before spindle start; wire 2NC into a dual-channel safety relay.
Inspection Hatches & Covers
Million-cycle mechanical life fits hatches that are opened every shift for cleaning or inspection.
Cost-Sensitive OEM Machines
The economical interlock tier of the DX family for circuits that need door detection but not door locking.
Coolant-Mist & Washdown Zones
IP67 resin head keeps working next to machining coolant, cleaning spray and dust.
Bolt-Plus-Interlock Assemblies
Mounts straight onto the DXL safety door bolt's pre-drilled pattern for a combined mechanical bolt + electrical signal unit.
Legacy Interlock Replacement
Plain NC/NO contact output drops into existing relay-based cabinets without rewiring to an electronic bus.
Frequently Asked Questions
What does positive break (forced separation) mean on the DX-D2/DX-D3, and why should I care?
When the actuator key is withdrawn, a rigid mechanical linkage pushes the NC contacts apart with at least 60 N of force over at least 10 mm of travel. If a contact has welded shut from an overload, the linkage still tears it open. That is the property a guard-monitoring circuit relies on: opening the door must open the NC channel no matter what state the contact is in.
Which of the four contact codes should I choose?
DX-D2-CO (1NC+1NO) covers a single-channel interlock plus a door-status lamp or PLC bit. DX-D2-2C (2NC) is the standard pick for a dual-channel circuit into a DQSRN or DA31 safety relay. DX-D3-2CO (2NC+1NO) adds a status contact on top of the dual channel. DX-D3-3C (3NC) suits three independent loops or series architectures that need a spare NC channel.
Can the DX-D2/DX-D3 keep the door shut while the machine coasts down?
No — these are monitoring-only interlocks with no locking segment. If your risk assessment shows a run-down hazard (spindles, flywheels, thermal processes), either specify a guard-locking switch such as the DX-D6 or DX-W2/W3/W5, or pair the DX-D2/D3 with the DXL mechanical door bolt, which has pre-drilled holes that accept these switches directly.
How do the 8 key insertion directions help during machine design?
The head accepts the DX-K actuator key from eight orientations, so the same switch body works whether the door hinges left or right, slides horizontally, or lifts vertically — you rotate the head rather than redesign the bracket. Combined with the DX-K range's fixed and adjustable key geometries, most door layouts can be covered without custom parts.
What are the electrical limits of the contacts?
Rated insulation voltage Ui 400 V, conventional thermal current Ith 8 A, rated operational point Ue AC 400 V / Ie 2 A. Treat the switch as a pilot device: route motor and heater loads through a safety relay or contactor, and let the DX-D2/D3 switch only the relay's input circuit. Electrical life is rated at 300,000 operations versus 1,000,000 mechanical.
Are these switches certified, and what standards do they follow?
The design follows IEC/EN 60947-5-1 and GB 14048.5-2017 (low-voltage switchgear, control-circuit devices and interlocks) — these are design and test reference standards. Certification documents are available on request; the safety performance actually achieved depends on your complete circuit, so validate at system level with the safety relay you deploy.
What should an export buyer confirm before ordering DX-D2/DX-D3?
Three things: the contact code (CO / 2C / 2CO / 3C) against your circuit design, the actuator key model from the DX-K range that matches your door geometry (keys are ordered separately), and quantity per shipment for pricing. Small trial orders are generally workable; contact the factory for current MOQ, lead time and OEM marking options.
Specs reviewed by Engineer Cai, Senior Application Engineer. See certificates.
Safety Light Curtain — Customer Cases
Real installations from DAIDISIKE clients. Click any case to view in full. Filter by scenario to quickly find a similar setup.