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Miniature Gear Pump Design and Manufacture

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We design small miniature gear pumps of about 25mm.

Mizuhata External Spur Gear Pumps

We are a family owned and operated custom gear manufacturer for over 6 decades. Using our basic technology in manufacturing small precision spur gears, we have moved into design and manufacture of the moving mechanisms for small or miniature external spur gear pumps.

Our gear pump mechanisms are used in lubrication pumps for machine tools. An actual example of our miniature gear pump mechanism is as shown above.

These gear pump mechanisms have been used in lubrication gear pumps to provide flow rate of 3 ml/min with lubricant viscosity of 32-1300mm²/s.

We welcome enquiries for our gear pump mechanisms, and our design and OEM manufacturing of miniature gear pumps.

Basic Information about Gear Pumps

The gear pump has a simple mechanism. The driving gear is rotated by a motor connected to the driving shaft. As the driving gear engages the driven gear, the fluid coming in from the inlet port is transferred via the outside of the gears between the teeth and the pump casing or housing, and then forced out under pressure into the outlet port of the pump. Gear pumps are normally used in applications with low to medium pressure output such as 2500-4000 psi.
While the driving gear rotates at 1750-3450 rpm, the gear pump is relatively quiet as the gears are supported by bushings or journal bearings on both sides. As there is no overhung bearing loading, the driving shaft will not deflect and cause wear easily. The areas of wear are the side plates which can be replaced or reground.
As gear pumps are good at controlling desired volume flow rate and can accomodate fluids of varying viscosity, they are used in precise metering applications, low-flow pumps, double pumps (mixing and blending), hydraulic, fuel and lubrication applications.

Efficiency of Gear Pump

Gear pumps operate typically at 85% efficiency. Efficiency can be calculated as follows:

E = P_out/P_in = (∆Pr*q)/P_in = (T*ω-P_loss)/P_in

E: Pump Efficiency;
P_out: Power Output to the Fluid System;
P_in: Power Input to the Drive Shaft;
∆Pr: Increase in Pressure between High Pressure Outlet and Low Pressure Inlet;
q: Fluid Flow Rate through the Pump;
T: Torque applied to the Drive Shaft;
ω: Angular Velocity of Rotating Drive Shaft;
P_loss: Loss in Power

For a given P_in, T and ω, reducing the gap between the sides of the gears and the side plates will increase ∆Pr and hence give higher gear pump efficiency, but below an optimum gap, increased friction between the gears and the side plates will increase P_loss, and thus lower the gear pump efficiency. P_loss is a function of friction and viscous effects, can only be determined experimentally.

We look forward to your miniature gear pump enquiry.