Miyachi Unitek offers a broad range of large-scale spot weld controls and spot welders. The product line includes spot welders that are capable of producing 4000 to 160,000 secondary amps. Our spot weld controls are available in two technologies, traditional single-phase AC and Inverters. A majority of our large-scale spot weld controls are manufactured California.

Traditional AC spot weld controls use alternating current to do the actual weld. The frequency at the welding electrodes is the same as line frequency, (typically 50 or 60 Hertz). The welding time, for spot welders, is controlled in Cycles. The spot weld control uses a large semiconductor switch, (an SCR or Silicone Controlled Rectifier), to control the power output.

As with all Miyachi Unitek spot weld controls, our AC controls were designed for repeatability – the ability to achieve the same weld quality consistently. Our goal is to bring under control the variables that affect the spot weld process. These variables include weld time, weld heat and force. Weld heat is controlled using closed-loop feedback. Using this feature, weld current is held constant regardless of material condition. Spot weld force is controlled using an electronic pressure regulator that delivers a precision air pressure to a pneumatic cylinder. With this feature installed, the force exerted by a pneumatic cylinder stays consistent from weld to weld. Our spot weld controls include monitoring capability to assure process consistency. Upper and lower limits can be set around monitored weld current to assure that proper current was delivered every time. If the process is outside of the set limits, the spot weld control will generate alarms.

Our traditional AC controls for spot welders are available with or without circuit breakers. They are also available with different numbers of SCR’s. Spot welders with greater numbers of SCR’s are capable of doing several welds on a part in a brief period of time.

Miyachi Unitek offers a line of Large-Scale inverter spot weld controls built to tackle the most demanding applications. Spot weld inverters create DC welding current that is more efficient and precise. Spot weld time can be programmed in one millisecond intervals for finite control. The inverters take closed loop control to a whole new level. Miyachi Unitek inverters constantly monitor primary current, secondary current and secondary voltage. Given this, the operator can choose the best closed-loop feedback method for specific materials or material conditions. Closed-loop feedback modes include Primary RMS, Secondary RMS, Primary Peak, Power RMS and Fixed Pulse. Spot weld conditions are monitored at very high speeds. All large-scale inverters have a 1kHz output – spot weld conditions are monitored real-time at this frequency.

Miyachi Unitek inverters assure process control for spot welders using an internal monitor. The internal monitor keeps track of spot weld time, weld current, weld voltage, weld power and inverter capacity usage. Upper and lower limits can be set around parameters so alarms can be produced if the process, for any reason, is out of control.

Inverters can also solve power issues typically associated with less sophisticated spot welders. Inverters draw equal current from each phase of a 3-phase power circuit. Less current is drawn due to the efficiency of DC welding. Also, inverters have almost unity power factor. If your facility has or creates light flicker, or if power factor or voltage drop in 3-phase lines is an issue, replacing older spot welders with inverters can help to solve the problem.