Semi Automatic Strapping Machine Fault Finder



Semi Automatic Strapping Machine Fault Finder only addresses those simple issues on popular machines that form 90% of a service engineers workload. As such, they are quick and easy to identify and  remedy,  and well within the scope of most works engineers.

Watch the video to check if your strapping machine operates like this

Do however first check with your  Health & Safety Officer before working on  these machines, and the manufacturers service manual for recommended procedures, as this advice is intended only to provide an opportunity for a competent person to 'Check the obvious' and avoid incurring the cost of a service call.

1. Strapping Machine does not power up:

  • Check  strapping machine is switched on
  • Check fuse in power supply cable
  • Check strapping machine fuse often located next to the motor run timer. 

2. Can't Feed Strap From Coilholder?

  • Check strap is streaming from top of coil ... NOT FROM THE BOTTOM.
  • Check strap is threaded correctly thru brake arm and guide rollers such that when strap is pulled brake arm lifts and allows coil of strap to rotate.
  • If when pulling strap brake lifts but coil does not rotate check strap is not trapped between side of coil and coil retaining disc. 

3. Can't Feed Strap From Coilholder up shute to table top?

  Fig:3  Semi Automatic Strapping Machine Top Strap Shute:

Switch Strapping Machine off and check strap shute is not blocked with strap debris This strap shute can be easily and  quickly checked by loosening screws and removing top half for access and inspection. The shute also has a moveable quadrant strap width adjuster, such that if straps are not aligned when joined in the area of the strap joint, the quadrant can be moved to narrow the effective width of the strap shute - and bring straps into line - but not too tight as the edge of the strap will fray and cause debris buildup, or block strap entry. Don't forget to reset the  strap width quadrant using a piece of strap as a guide, after any inspection.


FIG: 3A Semi Automatic Strapping Machine Feed & Tension Mechanism

Switch Strapping Machine off and check for strap blockage between feed and tensioning rollers Fig: 3A  If the strap appears to be jammed between them, using the length of strap exiting the machine cabinet at the aperture where it is normally fed into the machine
and into the feed rollers, pull it sharply downwards to free it. If the strap or debris cannot be pulled from the feeding/tensioning rollers the assembly can quickly be taken apart. i.e. Loosen set screw 1 - Remove pin 2 - Lift top roller assembly and inspect. If the area below looks clean then check strap infeed guide that is attached to the top RHS of the lower feeding/tensioning roller assembly.

If strap feeds thru all strap guides and feed/tensioning rolls and into sealing area of machine  but no further then the front strap gripper is probably in the raised position and blocking it, caused by the machine not finishing a complete strapping cycle. Three
options are available - press the re-set control on the front panel - turn motor switch 'off' then 'on' again - consult manual re: adjusting
micro switch lever LS1.

4. Strapping Machine Won't Seal the strap?

Semi Automatic Strapping Machine Heater Blade


Check that heater signal light - normally situated on the front control panel is on.If heater signal light is off check heater fuse.

With the machine switched off  and mains plug removed from socket,  test for circuit continuity across the heater blade terminals after first disconnecting the power  input cables to the blade.  Blade failure is uncommon however.

Check that there has been no significant change in ambient temperature e,g has machine been resited near an external open door.
If this is the case then locate the heater blade temperature controller commonly under the table top, unless digital control, and adjust
up by one position, allowing approx 60 seconds for the adjustment to take effect.

If the problem has ocurred immediately after a new and different specification of strap has been loaded onto the machine, adjust heater temperature control by one segment as the new strap may have a slightly different/higher melt point.

Switch machine off and after 5 minutes get access to a cool heater blade, and inspect for build up of melted strap residue. Remove if identified with fine emery cloth.

If checks  above indicate no fault, with machine switched off and heater blade cool, check alignment of the heater blade on its mounting bracket and that of the bracket on the reciprocating arm that pushes the blade under the anvil in between and out of the strapping, as the blade may have been bent or the mounting bracket misaligned such the blade does not slide between top and bottom straps horizontally.

Check that the reciprocating arm that holds the heater blade assembly moves forwards and backwards at approximately the same speed. Forward movement of this arm is generally governed by a cam, and it's return by a spring. Slow or no return indicates a spring has broken. No forward movement requires  service engineer attention.

5. Strapping Machine Won't Tension Strap?


          Semi automatic strapping machine tension1           Fig: 5A                        FigSemi Automatic Strapping Machine Tension 2: 5B   

       Semi Automatic Strapping Machine Tension 3              Fig: 5C


First - Check all drive belts are intact and under tension.

Check manual control tension knob - Fig:5A - has it inadvertently been turned to anticlockwise position.

Although it is seldom necessary, increase the tension between the two tensioning rollers very slightly by turning knurled wheel clockwise and securing with locknut   ( Fig:5B  )

Where internal tension mechanism is fitted (Fig: 5C) turn knob clockwise to increase applied yension as per external tension control.

Tension drive rollers may require replacement - see service manual.

6. Strapping Machine Won't Release Strap after sealing it?

                                                                                                                        Semi Automatic Strapping Machine Sealing Mechanism    

 This is often an indication that gripper bars and/or central pressure block have not completed their full operational cycle and simply pressing the re-set control normally positions these components in their default position allowing strap to pass. These components are actuated upwards in sequence by their individual cams to clamp the strap against the underside of the sliding anvil, and their release from the clamp position determined by springs. If the springs are worn or broken then the 'clamps' may not release the strap. These springs are accessible and easily replaced.  


Contact information.