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i4 | Inverter Resistance Spot Welder

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Components List | Specifications | Brochure

The i4 Inverter Resistance Spot Welder is designed to handle the difficult to weld materials such as boron steels and Advanced High Strength Steels (AHSS). These new metals are rapidly becoming the material of choice among car manufacturers. The i4 includes an OEM programmable feature with detailed repair illustrations and customized weld programs.

PS-500 Double-Acting Spot Gun

New innovative Spot Gun from Pro Spot features double-acting cylinder, wide-spreading electrodes, and self-aligning electrodes (see pictures in gallery). Push one button to open electrodes wide, then push the other button to close electrodes and weld. Pro Spot's PS-500 Spot Gun System features electrode pressure over 600 Lb. with all extension arm sizes. I-CAR minimum recommended squeeze pressure is 400lb.

Extension Arms

The i4 comes standard with several different types of weld arm extensions (508mm U-Arm, C-Arm, Wheelhouse Arm) and others are available upon request, so that you can tackle any welding problem with as much ease and accuracy as possible (see pictures in gallery).

Single-Sided Welding

10 different Single-Sided welding applications give you the power and versatility to complete any job. The i4 is capable of handling a variety of single-sided welding needs, including: washer, nut & bolt, nail, rivet and stitch (see pictures in gallery).

Control Panel (Front Panel)

The i4 features a clean, ergonomic interface layout with the power switch and electrode pressure knobs all set in a convenient and straight forward manner. It also has a large 4x6" monitor capable of displaying images and OEM repair procedures (see picture in gallery).

  1. Power Switch
  2. 3 Phase Power Indication Lights
  3. Electrode Pressure Gauge
  4. Electrode Pressure Control Knob
  5. Display Screen
Cooling System

The i4 is both water cooled and air cooled (see picture in gallery). The air cooling starts when the temp reach 42c and shuts off automatically at 37c. Welding can remain while air cooling is on.
The water cooling is loop based system that cools the transformer weld cables and spot gun. While the water cooling is running the welder can operate as normal.
The reason for the two cooling system is that Pro Spot found it being most efficient and will extend the duty cycle of the welder.

i4 Software

The i4 Software is stored on an upgradeable flash card. We consistently release the latest and newest repair procedures and features to keep you up to date.

i4s Software

MIG Combination

The i4 package can include a MIG welder (PR-155) as an option. It can also be installed later as an upgrade or ordered with MIG welder built-in from the factory. This feature allows the convenience of STRSW and MIG welding in one unit (see pictures in gallery).

MIG Features
  • 220V 1-phase ready to use
  • Binzel connector: quick-connect all-in-one adapter
  • Ideal for collision repair welding
Overhead Installation

The Pro Spot i4 is available in an overhead ceiling-mounted version. The ceiling-mounted version hangs from the ceiling at 20' bracket spacing giving you extra floor space and accessibility. With the overhead installation option, the welder hangs from a track system that can cover up to 14 bays (see pictures in gallery).

Overhead Features
  • All the features of a portable i4 welder. ( Optional MIG welder included. )
  • Convenient overhead mounting system.
  • No cables, air hoses or equipment on the floor.
  • Always connected, ready to weld.
  • Stores out of the way when not in use.
  • Moves easily around the shop.
  • Saves valuable shop floor space.
  • Inverter Technology, 2000Hz.
  • Liquid Cooled
  • Fully Upgradeable Software Stored On Removable Flash Card
  • Designed For New Advanced Steels: AHSS, HSS, T.R.I.P, BORON
  • Current Sensing Technology
  • OEM Repair Procedures On-Board
  • Multiple languages, Change On-The-Fly
  • 4 Cable System
  • 3-Phase Input
  • Double-Acting Spot Gun
  • Two Sided Spot Welding
  • Single-Sided Welding
  • X-Gun Adaptive (optional)
  • Upgradable To Overhead Installation (optional)
  • Built-In MIG Welder Available (optional)
Technical Specifications
Input Voltage 3 phases
  • 208 - 240v 50/60Hz
  • 400 - 420v 50/60Hz
  • 460 - 480v 50/60Hz
Welding Amperage: 12500A max (3-phase)
Cable Length: 8' (2.5m) standard
Electrode Pressure: 7 bars (90 PSI)-280 daN (616 Lb)
Cooling System:

Air (2 fans), Compressed air (weld gun and

weld cables) Water cooling (inverter,

transformer, welding gun)

Microprocessor: i4 Upgradable Software Platform
Protection: IP 21
Patents (3):

no. 5,239,155

no. 6,706,990

no. 6,539,770

Shipping Weight: 373lb (169kg)

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