Common Screw Types in Loss-in-weight Scales

The types of screws commonly used in loss-in-weight feeder and their advantages and disadvantages are listed below:

1. Single screw
Structural characteristics: single screw blade rotates around the center axis, simple structure, suitable for most materials.
Advantages:

• Low cost: simple structure, low manufacturing and maintenance costs.
• Strong versatility: Single screw loss-in-weight feeder suitable for conveying powder, granular and other non-sticky materials e.g. plastic granules
• Easy to clean: easy to disassemble, suitable for scenarios that require frequent material replacement.
  Disadvantages:
• Easy to clog: poor adaptability to viscous or easily clumped materials (e.g. wet powder, clay).
• Precision limited: lower conveying uniformity may affect high precision weighing.
• Fast wear: hard or high friction materials may cause fast blade wear.

2. Twin Screw
Structural features: Two intermeshing screws rotate synchronously for more uniform conveying.
Advantages:

• High precision: Double screw loss-in-weight feeder stable conveying, suitable for scenarios requiring high flow control (e.g. food additives).
• Self-cleaning ability: meshing design reduces material residue, suitable for sticky materials (e.g. chocolate syrup).
• Good anti-clogging: suitable for materials that are prone to bridging or clumping.
  Disadvantages:
• High cost: complex structure, high manufacturing and maintenance cost.
• High energy consumption: dual drive may increase power consumption.
• Limited scope of application: for ultra-fine powder may cause leakage due to clearance problems.

3. Belt Screw
Structural Characteristics: Screw blades are banded and have a large gap with the pipe wall.
Advantages:

• Low shear: suitable for brittle materials that are easy to break (e.g. potato chips, puffed food).
• Anti-adhesion: reduces material adhesion, suitable for materials containing sugar or grease (e.g. candy, nuts).
  Disadvantages:
• Low conveying efficiency: suitable for low speed and low capacity scenarios.
• Easy to wear and tear: low strength of belt blades, easy to deform in long term use.

4. Hollow Screw
Structural features: the center of the screw is hollow structure, which can pass coolant or heating medium.
Advantages:

• Temperature control: suitable for heat-sensitive materials (e.g. resin, chocolate) or materials that need to be heated and melted.
• Anti-curing: avoids cooling and hardening of materials during transportation.
  Disadvantages:
• Complicated structure: requires matching temperature control system, high cost.
• Maintenance difficulty: high sealing and anti-leakage requirements.

Suggestions for selection:

• Powder/granular material: single screw or twin screw (according to precision requirements).
• Sticky/caking materials: Twin Screw
• Heat-sensitive materials: Hollow screw.
• Brittle/friable materials: Belt screw.

The actual application needs to be combined with the material characteristics, cost budget and maintenance conditions of a comprehensive choice for loss-in-weight feeders.