Product Overview

This high‑precision screw valve meters hot‑melt adhesives and heavy pastes using a concentric screw drive running from 10 to 500 rpm. It handles viscous materials from about 5,000 up to 500,000 cps and produces steady output with repeatability near 98% after tuning. The valve features a short fluid path, quick‑release head and replaceable wetted parts to simplify cleaning and reduce downtime.

Problem

Many hot‑melt production lines suffer from variable bead width, missed deposits or frequent cleaning stops, which increase scrap and slow throughput.

Cause

Thick hot‑melt materials need positive displacement and steady feed; pumps relying on pressure or small clearances often pulsate, trap air, or wear quickly when handling heavy pastes. Wrong nozzle choice or unstable motor control further increases variation.

Solution

This screw valve uses positive displacement metering so flow tracks screw rpm linearly. The concentric screw design reduces dead volume and air pockets, giving consistent bead profile and fewer clogs. Replaceable mixer/nozzle parts and robust wetted materials reduce maintenance time and extend run intervals.

Application

• Hot‑melt bonding in electronics: adhesive dots and beads for connectors, housings and modules.
• Thermal interface assembly: dispense gap fillers and thermal adhesives for vapor chambers.
• Large pad or seam filling: structural bonding in power modules or motor assemblies.
• Automated cells: feeding downstream dispensers or direct bead application on conveyor lines.
• Pilot and production lines where long runs and minimal downtime are required.

How It Works

The concentric screw rotates to displace material forward; rpm sets flow rate so output scales with motor speed. The short central channel reduces trapped air and dead volume. Material is delivered to the mixer/nozzle where bead width and shot size are set by nozzle diameter and motor pulse length. For very heavy pastes, higher rpm and larger nozzle diameters improve flow.

How To Choose

1. Provide fluid viscosity at working temperature and any filler details so we can size screws and recommend clearances.
2. Select required peak and average flow per head and choose a model with margin above peak demand.
3. Pick nozzle diameter to match target bead width or dot size.
4. Choose inlet feed method (pressure pot for long runs; bulk feed for high volume). Use a stable regulator to avoid starvation.
5. Consider PTFE or ceramic wetted parts for abrasive or reactive adhesives.
6. Add encoder feedback or flow sensors for closed‑loop verification if required.
7. Request a bench test with your material to lock rpm, nozzle and heater settings.

FAQ

Q1: What does 98% repeatability mean for my line?
A1: It indicates shot‑to‑shot volume consistency after tuning with steady feed and correct nozzle; real results depend on fluid stability, feed method and tuning.

Q2: Can the valve handle abrasive or filled hot‑melts?
A2: Yes. Specify ceramic or coated screws and PTFE inserts for abrasive fillers. We recommend a bench test to estimate wear.

Q3: What driver and control do I need?
A3: A stable stepper or servo motor with speed controller is recommended. We can advise driver models and provide encoder options for better feedback.

Q4: How do I reduce cleaning downtime?
A4: Use the quick‑release head and replaceable mixer/nozzle elements. Schedule purge cycles and keep spare parts for fast swaps.

Q5: Do you provide sample testing with my adhesive?
A5: Yes. Send your hot‑melt sample, viscosity at application temperature and desired output; we will run trials and return a report with recommended settings.