EDM machine maintenance safety

⚠What laws and standards require

• Municipal fire prevention ordinances (EDM machines; model fire prevention ordinance, Article 10-2)

  An EDM machine that uses a hazardous material as the machining fluid must be fitted with: (1) a device that stops machining automatically when the fluid temperature exceeds the set temperature, (2) a device that stops it automatically when the fluid level falls below the setting, (3) a device that stops it automatically when it detects an abnormality such as growth of carbonized product, and (4) a device that extinguishes a fire automatically when the machining fluid ignites

  In 1991 the Fire and Disaster Management Agency added a standard for EDM machines to the model fire prevention ordinance. Article numbers differ by municipality (for example, Funabashi and Uruma: Article 10-2; Hiroshima and Fukuyama: Article 11-2; Sapporo: Article 14-2). Machines using water-based machining fluid are not covered^{[1][2][3][4][5][6][7]}

• Municipal fire prevention ordinances (management of EDM machines)

  Do not use machining fluid with a flash point below 70 °C. Do not perform machining that carries a fire risk, such as spray machining. Mount the tool electrode securely to prevent abnormal discharge. Carry out the necessary inspection and maintenance

  "Machining that carries a fire risk" includes dry discharge (sparking for positioning with the tank empty) and machining with the safety devices removed. In inspections, regularly check that the automatic stop devices and the automatic fire extinguishing system work, and keep a record of the results^{[3][4][5][7][2]}

• Operating standards of the fire prevention ordinances (fluid temperature and level settings)

  The temperature setting at which machining stops on fluid temperature is 60 °C or less. The fluid level setting is at least 50 mm from the top of the workpiece to the fluid surface

  The Hazardous Materials Safety Techniques Association's standard also sets the maximum allowable fluid temperature at 60 °C or less. It requires a design that stops the machine even when the level drops because earthquake shaking sloshes the fluid^{[4][3][5][7][2]}

• Fire prevention ordinances (standards for spark-producing equipment, applied correspondingly)

  Install it in a room where the wall, ceiling and floor surfaces facing the machine are finished with quasi-noncombustible material. Fit a ventilation system that removes flammable vapor. Keep the room tidy and clean, and do not use open flames

  The Hazardous Materials Safety Techniques Association's manual items also include not placing ignition sources such as heaters, welders and grinders around the work area^[3][2]

• Fire Service Act, Articles 10 and 11-4; Cabinet Order Concerning the Regulation of Hazardous Materials, Appended Table 3

  Most EDM oils are Class 4, Class 3 petroleum (designated quantity 2,000 L). Quantities at or above the designated quantity can be handled only in a licensed facility. From 1/5 up to under 1 of the designated quantity counts as a small quantity of hazardous material and falls under the municipal ordinance's standards and notification

  The quantity of hazardous material handled by an EDM machine is judged by the capacity of the machining fluid tank. Even when the quantity is under 1/5, the ordinance's standards for EDM machines themselves still apply^{[8][9][10][11][3]}

• Fire prevention ordinances (notification of installing equipment that uses fire)

  When installing an EDM machine that uses a hazardous material as the machining fluid, file an installation notification with the local fire department

  Sodick also says installation procedures under the Fire Service Act are required. The form and timing of the notification are set by each municipality^[3][12]

• Fire prevention ordinances (installing fire extinguishers)

  Even when an EDM machine is placed in a building where the Cabinet Order does not require fire extinguishers, provide a fire extinguisher

  The Sapporo explanation specifies a walking distance of 20 m or less from every part of the area to the EDM machine, an extinguishing agent suited to the machining fluid, and a capacity unit of 1 or more^[3](1 source, for reference)

• Hazardous Materials Safety Techniques Association's EDM machine type test confirmation

  A machine that has passed the safety confirmation test, which includes the ordinance's structural standards, is given an "EDM machine type test confirmation label"

  The fire service's operating standards say it is appropriate to use this label to confirm the structure. Check for it when buying or relocating a machine^{[4][3][5][6][2]}

• Standard for fire prevention of EDM machines (structure of the automatic fire extinguishing system)

  The automatic fire extinguishing system detects a fire automatically when the machining fluid ignites, stops machining, sounds an alarm, and extinguishes the fire. It can also be discharged manually

  The quantity of extinguishing agent is determined by the fluid surface area of the machining tank (maximum protected area). The system is marked with the type and quantity of agent, maximum protected area, discharge time, and the type and operating temperature of the detector^[2][3]

• Industrial Safety and Health Regulations (Japan), Article 107 (Stopping operation during cleaning, etc.)

  When cleaning, lubricating, inspecting, repairing or adjusting a machine is dangerous, stop operation, lock the starting device and fit a sign board or the like so that no one else can operate it

  This applies to maintenance work such as cleaning guides, re-positioning power feed contacts, replacing filters and resin, and cleaning the machining tank. Makino also recommends switching off the power and locking it out when shutting the machine down for a long time^[13][14]

• Preventing electric shock (do not touch the electrode side of an EDM machine)

  During discharge, do not touch the electrode-side parts such as the wire, electrode and rollers

  Niigata University's practical training textbook says that it can become dangerous at 50 V in normal conditions and at 20 V if hands and feet are wet, and teaches never to touch the electrode side (the opposite of the ground side). Safety requirements on the design side are covered by JIS B 6032^[15][16]

• Gas in die-sinking suction flushing

  When fluid is handled by suction, remaining gas can ignite or explode

  Take care with the suction position and force^[17](1 source, for reference)

• Safety data for EDM oil (precautions in product data)

  Wear protective gloves, safety glasses and the like. If swallowed and drawn into the airway, it can be life-threatening. If it gets on the skin, wash well with soap and water

  High-flash-point oils produce less fume and mist and are said to help improve the working environment^{[10][18][19][20]}

• Safety data sheet for graphite (dust when machining electrodes)

  Where graphite dust is produced, use local exhaust ventilation or general ventilation. When a certain amount of powder is suspended in the air, there is a risk of dust explosion

  The ACGIH threshold limit value (TLV-TWA) for graphite is 2 mg/m³. It applies when machining graphite electrodes on a machining center or similar^[21](1 source, for reference)

• JIS B 6032:2025 (Machine tools — Safety — Electrical discharge machines)

  A safety standard for machine designers and manufacturers that also specifies the information the manufacturer must give the user (such as the contents of the instruction manual)

  The 2025 revision aligns with ISO 28881:2022 while changing content to suit Japan's fire prevention ordinances and the like. Risk assessment examples are in TR B 0035^[22][16][23](1 source, for reference)

The legal provisions are summarized in Kezuriba's own words. Check the exact wording against the original text in e-Gov Law Search.