Extruder Gear Pump

Melt Pump Applications

• Sheet and Film Extrusion (tape plant, woven sack plant, lamination and PP plants, box stapping plant, mono filaments, non-woven fabrics)
• Compounding (master batch)
• Pipe/Profile/Cable Extrusion
• Rubber Extrusion

Technical Specifications

• Materials: PET, PS, PP, PE-LLD, PE-HD
• Throughput: 30-12,000 kg/h [66-26,400 lb/h]
• Difference Pressure – standard (max.): 250 bar [3,626 psi]
• Difference Pressure – option (max.): 500 bar [7,252 psi]
• Viscosity: 5-20,000 Pas
• Temperature (max.): 350°C [662°F]
• Misc.: Full nitriding depth of gear teeth (unique among melt pump manufacturers)
• Melt Pump Manufacturer: Eprotec (made in Switzerland)

Output Melt-X Models (in kg/h):

Model	Flow Rate (ccm/rev.)	PE-HD pipe	PE-LD film	PP sheet	PS sheet	PET sheet
melt-X1	25.5	105	140	160	200	220
melt-X2	45.2	180	240	260	320	350
melt-X4	90.0	300	400	480	570	600
melt-X7	175.9	500	700	850	1,100	1,200
melt-X10	364.0	830	1,300	1,500	1,900	2,100
melt-X20	706.0	1,400	2,200	2,400	3,100	3,400
melt-X40	1463.0	2,400	3,800	3,900	4,900	5,400
melt-X80	3140.0	6,300	7,500	8,000	10,000	12,000

Output Melt-X Models (lb/h):

Model	PE-HD pipe	PE-LD film	PP sheet	PS sheet	PET sheet
melt-X1	231	308	352	440	484
melt-X2	396	528	572	704	770
melt-X4	660	880	1,056	1,254	1,320
melt-X7	1,000	1,540	1,870	2,420	2,640
melt-X10	1,826	2,860	3,300	4,180	4,620
melt-X20	3,080	4,840	5,280	6,820	7,480
melt-X40	5,280	8,360	8,580	10,780	11,880
melt-X80	13,860	16,500	17,600	22,000	26,400

Melt Pump – Special Options

Model	Application	Description	Examples
melt-XS	Thermally critical materials	Lubrication flow and drainage is led outside: for optical/transparent and shear-sensitive and temperature-sensitive polymers	PC (polycarbonate), PMMA (polymethylmethacrylat), TPE-V, PE-X
melt-XC	Thermally critical materials	Circulation loop for better temperature control: to reduce temperature increase of polymer	automotive TPO profiles
melt-XMB	Low-viscosity materials	to process extremely low-viscosity materials (such as MFI 1500)	PP (polypropylene) in mask filter production
melt-XH	High-pressure	For materials and applications that generate high pressure up to 500 bar [7,252 psi]	highly viscous polymers, elastomers, small micro granules, thin profiles and tubes
melt-XR	Abrasive material with high filler content	to process material with high filler content, e.g. 83% CaCO3, 80% BaSO4 or 50% glass fiber	recycling and compounding
ATEX EX II	ATEX environments	Temperature control with thermal fluid (oil)	ATEX environments
Pump with Amorphous Surface	All applications	Amorphous surface prevents material build-up and allows faster color change	all applications

Melt/Gear Pump Function in Plastic Extrusion

Fig.1: Two externally toothed gear wheels mate with each other when they rotate (counter-rotating non-intermeshing). A small pressure, generated by the extruder installed upstream, is sufficient to fill the tooth chambers (Fig. 1)

Fig 2: On the discharge side, the mating of the gear teeth in each other conveys the melt out of the tooth chambers.

Fig 3: The forces on each of the gear shafts are taken up by two slide bearings. These are lubricated by the plastic and are maintenance-free

Melt Pump Control

There are different ways to synchronize the melt pump with the extruder. The control unit of the extruder may already have the option to implement an external device such as a melt pump. Or the melt pump is operated with a separate melt pump control unit which synchronizes extruder and melt pump (either via 0-24V DC or 0-10V DC control signal). Here the two most common melt pump control modes are the so-called ‘extrusion mode’ and ‘compounding mode’

• Extrusion Mode:
  The pump inlet pressure (P1) is measured by a pressure gauge. The melt pump control compares the set pressure with the actual pressure and then regulates the extruder screw speed.
• Compounding Mode:
  The pump inlet pressure (P1) is measured by a pressure gauge. The melt pump control compares the set pressure with the actual pressure and then regulates the speed of the melt pump.

How to choose the right melt pump?

When choosing a melt pump for extrusion following criteria must be considered:

• Flow Rate (minimum, maximum, normal)
• Inlet and Discharge Pressures (minimum, maximum, normal)
• Application (e.g. Compounding, Sheet/Film extrusion, Rubber extrusion etc.)
• Type of Polymer & Viscosity (e.g. PP, PET, HDPE etc.)
• Temperature (minimum, maximum, normal)
• Filler Content (percentage and kind of filler/solids)

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