I. Appearance Inspection

Surface Quality

The product surface should be free of obvious scratches, abrasions, dents, protrusions, and other defects.

The surface roughness should meet the design requirements and can be measured using a roughness tester.

There should be no oxidation, rust, black spots, or other undesirable phenomena.

Color and Gloss

The product color should be uniform and consistent, with no significant color difference compared to the standard color chart.

The surface gloss should meet the requirements and should not be dull, lackluster, or excessively reflective.

Edges and Corners

The edges of the product should be neat and free of burrs and flash.

The corners should be clear and distinct, and there should be no rounded corners or collapsed corners.

II. Dimensional Inspection

Basic Dimensions

Use measuring tools (such as calipers, micrometers, three-coordinate measuring machines, etc.) to measure the basic dimensions of the product, such as length, width, height, and diameter. The dimensional deviation should be within the tolerance range specified in the design.

For critical dimensions, multiple measurements should be taken, and the average value should be used to improve measurement accuracy.

Form and Positional Tolerances

Planarity: Measure the planarity of the product surface using a planarity tester or a three-coordinate measuring machine. The deviation should meet the design requirements.

Perpendicularity: Use a square, dial indicator, and other tools to measure the perpendicularity between different parts of the product. The deviation should be within the specified range.

Parallelism: Use a parallelism tester or a three-coordinate measuring machine to measure the parallelism between two planes or axes of the product to ensure that it meets the design standards.

Roundness and Cylindricity: For circular parts, use a roundness tester or a three-coordinate measuring machine to measure their roundness and cylindricity. The deviation should not exceed the specified value.

III. Performance Inspection

Hardness

According to the requirements of the product material, use a hardness tester to test the product hardness to ensure that the hardness meets the design standards.

Different parts may have different hardness requirements; multiple point measurements should be performed.

Strength and Toughness

Test the strength and toughness of the product through tensile tests, impact tests, etc., to ensure that the product can withstand the corresponding loads and impacts during use.

The test results should meet the product design requirements and relevant standards.

Sealability

For products with sealing requirements, such as valves and pump bodies, a sealing test should be performed.

Pressure tests and leakage tests can be used to ensure that the product has no leakage under the specified pressure.

IV. Other Inspections

Identification and Packaging

The product should be clearly marked with the product name, model, specifications, production date, and manufacturer.

The packaging should meet the requirements for transportation and storage to ensure that the product is not damaged during transportation.

Sampling Inspection

Inspect the products according to a certain sampling ratio to ensure the stability and consistency of product quality.

The sampling plan should be determined based on factors such as the batch size and quality requirements of the product.

In summary, the inspection standards for CNC machined products should strictly follow the design requirements and relevant national and industry standards to ensure that the product quality meets the requirements and provides reliable products for users.

Splines, keys, half-round keys, and Woodruff keys all transmit mechanical torque. Longitudinal keyways are machined on the shaft's outer surface, and the rotating parts fitted onto the shaft also have corresponding keyways to maintain synchronous rotation with the shaft.
While transmitting torque, some spline shafts can also slide longitudinally on the shaft, such as the spline shafts used in gearbox shift gears.

Common Types:
Rectangular spline shafts: Widely used in aircraft, automobiles, tractors, machine tool manufacturing, agricultural machinery, and general mechanical transmission devices. They offer numerous advantages: high load-bearing capacity due to multiple teeth in operation; good centering and guiding properties, ensuring transmission accuracy and stability; shallow tooth roots, minimizing stress concentration and reducing shaft and hub strength weakening; relatively easy machining, achieving high precision through methods such as grinding. Rectangular spline shafts are available in light and medium series according to standards.
Involute spline shafts: Suitable for connections with high loads, high centering accuracy requirements, and larger dimensions. Their tooth profile is an involute, and radial forces act on the teeth under load, providing automatic centering and ensuring even load distribution across the teeth. They are characterized by high strength and long life. The machining process is the same as for gears, easily achieving high precision and interchangeability.

Machining Methods:
Rolling method: Using a spline rolling cutter on a spline shaft milling machine or rolling machine using the generating method. This method offers high productivity and precision and is suitable for mass production.
Milling method: On a universal milling machine, using a special forming cutter to directly mill the tooth profile. Teeth are milled one by one using an indexing head; if a forming cutter is not used, two face mills can also mill both sides of a tooth simultaneously, milling each tooth before slightly finishing the bottom diameter with a face mill. The milling method has lower productivity and precision and is mainly used for single-piece and small-batch production of spline shafts with external diameter centering and rough machining before hardening.
Grinding method: Using a shaped grinding wheel on a spline shaft grinding machine to grind the spline tooth flanks and bottom diameter. Suitable for machining hardened spline shafts or those with higher precision requirements, especially those with internal diameter centering.
Cold heading method: Performed on specialized machines. Two heading tools are symmetrically arranged on the outer circumference of the workpiece. With the workpiece's indexing rotary motion and axial feed, the workpiece rotates by 1 tooth, and the forming wheel on the heading tool strikes the workpiece tooth groove once. Under the continuous high-speed, high-energy impact of the rotating wheel, the workpiece surface undergoes plastic deformation to form the spline. The precision of cold heading is between milling and grinding, and the efficiency is about 5 times higher than milling, also improving material utilization.

Classified by gear meshing type:
External meshing gears: Two gears mesh externally within the pump casing; one is the driving gear, and the other is the driven gear. This type of gear pump is simple in structure, easy to manufacture, and widely used. Its working principle is that when the driving gear rotates, it drives the driven gear to rotate in the opposite direction, thus creating a change in the space between the gear teeth, achieving the suction and discharge of liquid. For example, external meshing gear pumps are often used in small oil pumps and water pumps.
Internal meshing gears: The two gears in this type of gear pump have different shapes and numbers of teeth. One is an annular gear that can float in the pump body, and the other is a driving gear that is eccentric to the pump body. The annular gear has one more tooth than the driving gear. The driving gear drives the annular gear to rotate together, using the change in space between the two teeth to transport liquid. Compared with external meshing gear pumps, internal meshing gear pumps are smaller in size and have more uniform flow, but they are relatively more complex to manufacture and are often used in situations with high requirements for space and flow stability.

Classified by tooth profile:
Involute tooth profile gears: The tooth profile is an involute curve, with advantages such as smooth transmission, low noise, and high load-carrying capacity. It is the most commonly used tooth profile in gear pumps. Most pump gears under normal operating conditions use involute tooth profiles, which can meet general fluid transport needs.
Cycloidal tooth profile gears: Gear pumps with cycloidal tooth profiles are also called cycloidal gear pumps, and their tooth profile curves are formed by cycloids. This type of gear pump is characterized by its compact structure, small size, and large displacement, making it suitable for situations with space limitations and high displacement requirements, such as small hydraulic systems.

Classified by tooth surface type:
Straight tooth gears: The direction of the teeth is parallel to the gear axis, which is the simplest form of gear. Straight tooth gear pumps have advantages such as simple structure, easy processing, and low cost. They are more commonly used in high-pressure conditions because there is no axial thrust, and the transmission efficiency is higher. However, straight tooth gear pumps have larger flow pulsations and relatively higher noise.
Helical gears: The direction of the teeth is at a certain angle to the gear axis. The meshing of helical gears is gradual, so the pulsation during the conveying process is smaller, and it is quieter at higher speeds. However, helical gears generate axial loads, requiring higher bearing requirements.
Herringbone gears: Composed of two helical gears, shaped like the letter "V". Herringbone gears combine the advantages of straight and helical gears, such as smooth conveying, small pulsation, and high load-carrying capacity. However, they have larger shear forces, which can easily cause material thermal degradation. They are usually used in situations with high requirements for conveying stability.
Circular arc tooth surface gears: The tooth surface is circular arc-shaped. This type of gear has high load-carrying capacity, low wear, long service life, and can reduce fluid leakage, improving pump efficiency. Circular arc tooth surface gear pumps are more commonly used in situations with high performance requirements for pumps, such as high-precision hydraulic systems and chemical processes.