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418 Style Bag Machine Basics

 

The 418 style bag machine provides an infinitely varied dwell times, heats, and seal pressures. This capability makes the machine a very versatile and easily operated and maintained piece of equipment.

 

It uses a hydraulic cylinder to move a set of driven idler rolls back and forth under a seal head and platen. The effect of the shuttle moving back and forth is a freeze in the movement of the film for a short time allowing the seal head to come down into the platen, which seals and perforates the film.

 

Always lock out the machine to work on moving parts or electrical systems.

 

The machine runs off of 240v or 480v 3phase power. It must be phased properly for Seal Head Pump to rotate in the correct direction or the head will not lift up. This is most evident when the machine has just been changed out.

 

Things to look for when running the bag machine.

 

Varying bag length

  • Improper shuttle pressure

  • Loose or faulty timing belts

  • Improper nip pressure or slippage of web through the nips (slip, ink buildup, etc.)

  • Air leak at bellowfram on dancer allowing machine speed to be erratic

  • Mechanical bind of shuttle assembly

  • Low on hydraulic fluid or air in hydraulic fluid

  • Faulty variator

  • Improperly set variator (web slack)

  • Improperly set volume control

  • Bag length set to high (mechanical models can bind up or lock up on the variator side)

  • Dwell time set to high (electrical and mechanical models if dwell is set longer that the shuttle cycle time, the machine will chop off or have erratic shuttle motion)

 

Poor Seals

  • Keep web slightly relaxed with variator

  • Improper temperatures

  • Improper dwell times

  • Improper seal head pressure

  • Check condition of teflon tape and curtain

  • Check for foreign material under the curtain, or build up on aluminum seal heads

  • Check bag machine rubbers

  • Remove banding from machine platen

  • Loose standoffs on seal head

  • Check for mechanical slack in the sealing head drive train. Turnbuckles, spherco bearings, pivot bushings. The Sealing head when pushed up should not have any movement. If there is movement, there is slack in the seal head drive train. This will give erratic seals and break blades.

  • Faulty head firing relay  (evident by erratic seals or double cycling of the seal head)

  • Improper phase adjustment for the head firing timing

  • Faulty or improperly adjusted microswitch

  • Loose or faulty timing belts

  • Improperly set volume control

  • Improperly set variator (web slack)

  • Faulty electrical connections to seal head resulting in erratic temperature

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