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Randcastle Microtruders

Randcastle Microtruder Models

The use of Hot-Melt Extrusion (HME) for manufacturing complex drug delivery systems has recently been receiving a lot of interest because it offers a number of advantages over traditional, wet mass based pharmaceutical manufacturing processes.

With batch sizes as small as 10 grams, the Randcastle Microturder line of small, vertical, single screw lab extruders are ideal for R&D HME applications where materials are particularly scarce or expensive. Production rates from 5 grams up to 34 kilos/hour are possible. Randcastle’s patented Recirculator Mixing Technology achieves dispersive and distributive mixing similar to horizontal twin-screw HME extruder designs.

The vertical screw design is discharge driven, which efficiently “pulls” the material through the extruder, thus using the strongest part of the shaft for the highest forces. (As an analogy, think about pulling a rope, rather than pushing a rope.) Rancastle extruders can achieve high pressures with small, thin screws down to ¼ inch in diameter. The screws can be made longer, if required, for more efficient pumping and mixing. (Screws are typically supplied with a 36:1 L/D ratio; however, lengths up to 50:1 are possible.) The vertical screw extruders also have an overall footprint smaller than conventional twin-screw designs. 

Randcastle’s patent-pending melting technology combined with the relatively small sizes of the Microtruders results in better melting at lower temperatures with reduced residence time, which prevents polymers from being overheated. Randcastle has also developed Surge Suppression Technology for smoother pumping for a more uniform product. Electric heaters are used to heat the material in the barrel and die. Water-jacketed feed coolers keep the feedstock cool to ensure proper flow of material.

The vertical screw extends into the feedstock to provide uniform feeding, even with poorly flowing materials. Randcastle offers a range of interchangeable feed sections and feeding solutions to further improve material flow.

Pharmaceutical Applications:

  • Pelletizing
  • Granulating
  • Thin-Film Oral Release Drug Delivery Systems (PharmFilm)
  • Sustained Release Tablets
  • Compounding/Mixing
  • Nano-Compounding
  • Transdermals/Transmucosals

 Other Applications:

  • Co-Extrusion
  • Film Extrusion
  • Extrusion Molding
  • Blown Film
  • Medical Devices
  • HME technology for mixing/compounding, granulating, pelletizing, sustained release and thin film pharmaceutical delivery systems forms.
  • Small-scale bench-top units for R&D and production. Batch sizes as small as 10 grams are possible.
  • Randcastle's patented Recirculator (Elongation Mixing) elements mix as well as conventional twin-screw designs for very good dispersive and distributive mixing/compounding.
  • Thorough mixing, even with high filler loading.
  • Randcastle's patent-pending zoned melting system ensures even melting with high output without excessive heat or hot spots, which can degrade the product.
  • Randcastle's patented Surge Suppression system results in a more uniform product
  • Since Randcastle screws are in tension (rather than compression) they can be made longer for even better mixing and melting. Very long screws with a L/D (length to diameter) ratio of 50:1 are possible.
  • Different interchangeable stainless steel feed sections are available to suit the material being processed. Feed sections can be changed without having to disassemble the entire extruder. Feed sections employ water jackets to keep the product cool for smooth flowing before entering the extruder.
  • Randcastle micro extruders work very well with low-density polymers. A paddle attached to the top of the screw with the screw extending into the feedstock ensures the material reaches the screw for better feeding without bridging.
  • Stainless steel construction.
  • Electric barrel heaters for heating the melt. Optional higher temperature electric are available.
  • Thermocouple and pressure ports.
  • Randcastle’s discharge-driven vertical screw is 2 to 4 times stronger than equivalent horizontal screws. (This is because Randcastles screws are driven through the metering section—the strongest part of the screw.)
  • Because Randcastle's screws are so strong, they can be cut deeper for higher output.
  • Faster Screw Speeds (up to 350 RPM) for higher output for a given screw diameter.
  • Randcastle’s side discharge prevents pressure from pushing on the tip of the screw so you can run much higher pressures.
  • Bench mounting is standard; rotating the flange on the gearbox can change the direction of extruder’s output. Adjustable height levelers are provided so that the height of the extruder can be easily adjusted.
  • Separate control cabinet with digital ammeter with over amperage shutdown, control and digital readout of screw RPM, digital heater controls with auto-tuning for barrel and die.
(In Inches)
(Max1 Inches)
RCP-0250 0.250 10 to 115 grams 0.03 0.33 1.3 cm3 460 cm3
RCP-0375 0.375 29 to 352 grams 0.06 0.75 5 cm3 1,925 cm3
RCP-0500 0.500 82 to 983 grams 0.132 1.0 15 cm3 1,925 cm3
RCP-0625 0.625 168 to 2040 grams 0.15 1.5 34 cm3 1,925 cm3
RCP-0750 0.750 0.5 to 6 pounds 0.18 2.0 73 cm3 325 cm3
RCP-1000 0.100 1 to 18 pounds 0.19 3.0 107 cm3 700 cm3
RCP-1250 1.250 1.9 to 35 pounds 0.21 5.0 283 cm3 1,600 cm3

Outputs shown here are for guidance only and were dreive from machines run under typical conditions.. Actual output will depend on many factors.

  1. If this dimension is close to the maximum feed stock dimension, lab testing might be prudent to insure performance.
  2. A standard RCP-0500 screw will accept most conventional 1/8 inch pellets.
  3. The volume of low output screws is about 60% less and the free volume of highoutput 50:1 L/D Recirculator screws about twice as high.
  • Different styles of interchangeable smooth-bore and grooved feed sections as well as roller feeders for strip stock
  • Pressure Monitoring Package, with pressure transducer and digital pressure indicator (highly recommended)
  • Enhanced instrumentation package, for recording viscosity, pressure, temperature, RPM, amperage, torque, feed rate, vacuum and other parameters
  • High Temperature Heaters for 200 to 400C operation
  • Extra Die Heating Zone with digital auto tuning temperature controller
  • Barrel Cooling Package with upgraded heating/cooling controllers with independently controlled fans for each barrel zone for much better control
  • High and Ultra High Performance Elongator Melting/Mixing Sections for the distributive mixing performance of a twin screw extruder
  • Air Cooled Filament Conveyor Line
  • Starve Feeder-Belt type feeder
  • Micro-Feeder volumetric feeder for feeding small quantities of powder over a period of time
  • Additional vents for gas extraction.
  • Additional inlet ports are available for side stuffer feed, overhead gravity feed, liquid and melt feed.
  • In-line Rheometer
  • Gear pumps for volumetric pressure stability and a more uniform product
  • Link multiple extruders (example: Compound in one and degas in another) or Extend your L/D to over 200:1 with 4 extruders
  • Special plating to protect against wear, corrosion or improve performance
  • Winder
  • Chill roll
  • And many more are available. Please contact us if you have a requirement for something that is not on this list.