Comparing Central Conveying to the Alternatives

Let’s examine the alternatives to an automated resin conveying system and consider what can be accomplished with the installation of a central system.

Invariably, if you are a plastics processor, you have to move resin from one place to another….sometimes from multiple sources to multiple destinations.

Here are the basic material sources and their possible destinations…

Resin may arrive at your plant in:

  • Bags
  • Boxes
  • Gaylords
  • Super sacks
  • Bulk truck
  • Rail car

You may have to move that material to:

  • Silos
  • Surge bins
  • Drying hoppers
  • Blender hoppers
  • Machine throat

Additionally you may want to transfer regrind from granulators back into the production stream.

There are multiple ways to move the resin.

Move resin manually with a bucket and ladder

Pros:

  • Buckets and ladders are inexpensive

Cons:

  • Very labor intensive so costs are high
  • Climbing ladder increases chance of employee injury
  • Resin spills on the floor, further increases costs and chance of injury
  • Hoppers may run low on material resulting in short residence times and poorly dried material
  • Molding machines are frequently starved for material
  • High percentage of rejected parts due to resin contamination and poor drying

Use Vacuum Loaders to move material from gaylords to destination

Pros:

  • Self contained loaders are relatively inexpensive and easy to set up

Cons:

  • High energy consumption
  • High labor costs to replace brushes and motors
  • Gaylords remain on production floor
  • Space required to allow forklifts to deliver Gaylords

Use a screw auger device to twist and grind the material up to its destination

  • Better than the bucket brigade
  • May be used for starve feed applications

Cons:

  • May produce undesirable fines and debris on the floor resulting in injuries
  • Bulky drive system takes up a lot of floor space
  • Labor intensive due to constant monitoring
  • Results in high % of rejects when flow is interrupted

Blow resin with a compressed air venturi loader.

  • Inexpensive to purchase.
  • Low material delivery rates
  • Compressed air required
  • Blows fines into the environment creating housekeeping problems

Blow resin with pressure blower and air lock device.

  • Very high delivery rates.

Cons:

  • High equipment investment
  • Blows fines into the environment creating housekeeping problems
  • Requires a cyclone to separate air from material

Use central vacuum conveying system to convey resin from one or more locations to one or more destinations

Pros:

  • Moderately priced
  • Delivery rates to match any requirement
  • Maximizes machine up-time
  • Improves uniformity of product quality
  • Maximizes use of floor space by minimizing congestion around the machines
  • Allows material validation and verification
  • No fines blown into the environment
  • Greatly improved housekeeping – reducing injuries
  • Minimizes material waste
  • Expandable with several system configurations
  • Easily integrated with silos, blenders, dryers, surge bins, etc.
  • Can be integrated with plant-wide monitoring and control systems
  • Minimizes human intervention in the process to ensure lower labor costs

Cons:

  • Personnel may need to be re-trained to operate larger systems.
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