China Press Brake Noise Standard GB/T 24388-2009: Limits & Testing Guide

This post is also available in:

Chinese press brake manufacturers commonly use GB/T 24388-2009 as a technical reference for evaluating machine noise during factory inspection. The standard defines A-weighted sound power and sound pressure limits for press brakes according to drive type and nominal force, and it references standardized methods for measuring both values.

GB/T 24388-2009, officially titled “Noise Limits for Press Brake and Flanging Machine,” remains a current Chinese national standard. It has been a recommended rather than mandatory standard since March 2017. As of 2026, a revision project is under development, but GB/T 24388-2009 remains the current published version.

For overseas buyers, this standard is useful for understanding how a Chinese press brake manufacturer may evaluate noise performance before delivery. It should not, however, be confused with workplace noise exposure regulations in the destination country.

What Does GB/T 24388-2009 Cover?

GB/T 24388-2009 specifies noise limits for press brakes and flanging machines rather than setting one universal dB value for every machine.

The permitted noise level varies according to:

• Machine transmission type
• Nominal force
• Whether sound power or sound pressure is being evaluated
• Operating condition
• Measurement method

This distinction is important because a small hydraulic press brake and a large hydraulic machine above 2500 kN are not evaluated against the same numerical limit.

GB/T 24388-2009 at a Glance

What Is the Difference Between Sound Power and Sound Pressure?

Sound power and sound pressure describe different aspects of machine noise and should not be treated as interchangeable values.

A-Weighted Sound Power Level — LWA

Sound power describes the acoustic energy emitted by the machine as a noise source.

It is primarily used to characterize the machine itself rather than the sound level experienced at one specific operator position.

GB/T 24388-2009 specifies maximum A-weighted sound power levels for press brakes during continuous no-load operation.

A-Weighted Sound Pressure Level — LpA

Sound pressure describes the noise measured at specified positions around the machine.

The measured value can be affected by factors such as:

• Measurement position
• Distance from the machine
• Workshop acoustics
• Background noise
• Operating condition

For this reason, a sound pressure result should always be interpreted together with the measurement method and test condition.

What Are the Sound Power Limits for Press Brakes?

The allowable A-weighted sound power level under GB/T 24388-2009 depends on both transmission type and nominal force.

During continuous no-load operation, the A-weighted sound power level LWA should not exceed the following values.

A-Weighted Sound Power Level Limits

The table shows why it is incorrect to describe one figure such as 75 dB(A), 80 dB(A), or 85 dB(A) as the universal noise limit for all press brakes.

A manufacturer should first identify the machine type and nominal force before applying the relevant limit.

What Are the Sound Pressure Limits for Hydraulic Press Brakes?

Hydraulic press brakes have separate A-weighted sound pressure limits according to nominal force.

During continuous no-load operation, the A-weighted sound pressure level LpA measured at the specified positions should not exceed the following values.

A-Weighted Sound Pressure Level Limits

For example, a hydraulic press brake with a nominal force between 630 kN and 2500 kN is evaluated against an LpA limit of 85 dB(A) under the specified no-load test condition.

This does not mean that every measurement taken anywhere around the machine must always remain below 85 dB(A). The operating condition, measurement position and applicable test method must also match the standard.

What Is the Impulse Noise Limit for Mechanical Press Brakes?

Mechanically driven press brakes are also subject to impulse sound pressure limits because a single machine stroke can generate short-duration impact noise.

For mechanically driven press brakes operating under a single no-load stroke, the A-weighted impulse sound pressure level LpAI should not exceed the following values.

This requirement is particularly relevant to mechanical-drive machines because their noise characteristics differ from those of modern hydraulic or servo-electric press brakes.

How Is Press Brake Sound Pressure Measured in China?

GB/T 23281-2009 provides the referenced method for measuring sound pressure levels of metal-forming machinery.

Its official English title is “Metal forming machinery — Noise measurement method of sound pressure levels.” The standard is currently listed as valid by China’s national standards platform.

A meaningful test should identify at least:

• Machine model
• Nominal force
• Drive type
• Operating condition
• Measurement position
• Background noise
• Measuring instrument
• Test environment

The operating condition is especially important.

A result measured during continuous no-load operation should not be directly compared with a short peak recorded during actual sheet bending.

These represent different machine conditions.

How Is Press Brake Sound Power Measured?

GB/T 23282-2009 provides the referenced method for determining sound power levels of metal-forming machinery.

The official English title is “Metal forming machinery — Noise measurement method of sound power levels,” and the standard is currently valid.

Sound power measurement evaluates the machine as an acoustic source rather than simply recording the noise at one operator position.

This is why LWA values are normally higher numerically than LpA values in the GB/T 24388 tables.

Buyers should therefore avoid comparing:

100 dB(A) LWA

directly with:

85 dB(A) LpA

as if the two values represented the same measurement.

They do not.

Why Is Continuous No-Load Operation Used for the Limit Test?

A defined no-load condition makes machine-to-machine noise evaluation more repeatable.

Actual bending noise depends heavily on the workpiece and tooling.

For example, operating noise during production can change with:

• Sheet thickness
• Sheet dimensions
• Material grade
• Punch and die geometry
• V-opening
• Bending speed
• Workpiece vibration
• Sheet support
• Contact between material and tooling

If every manufacturer tested a different sheet and bending process, the results would be difficult to compare.

A defined no-load operating condition therefore provides a more consistent basis for evaluating the machine itself.

What Normally Causes Noise on a Hydraulic Press Brake?

The hydraulic system is one of the main continuous noise sources on a conventional hydraulic press brake, but it is not the only source.

Common contributors include:

Hydraulic Pump and Motor

The pump and electric motor generate continuous operating noise while the hydraulic system is running.

Pump condition, installation quality and hydraulic design can all influence the resulting sound.

Hydraulic Flow and Valve Operation

Pressure and flow changes through the hydraulic circuit can produce additional noise.

Abnormal cavitation, pressure fluctuation or poor component condition may also increase hydraulic noise.

Machine Structure and Vibration

Machine panels, hydraulic pipes and mechanical components can transmit or amplify vibration.

Correct installation and component mounting therefore affect the final acoustic behavior.

Tooling and Workpiece Contact

Actual bending introduces noise that does not exist during a no-load test.

The punch, die and sheet may produce impact or vibration during:

• Sheet positioning
• Tool contact
• Bending
• Material springback
• Workpiece handling

This is why production noise and standard no-load machine noise should be described separately.

Are Servo-Electric Press Brakes Quieter Than Hydraulic Press Brakes?

Servo-electric press brakes can reduce some continuous hydraulic noise because they do not use a conventional hydraulic pump system for ram movement.

During standby and some non-bending operating stages, this can result in a noticeably different acoustic environment compared with a conventional hydraulic press brake.

However, an electric drive does not eliminate all machine noise.

Actual bending still involves:

• Mechanical drive movement
• Tool contact
• Sheet vibration
• Backgauge movement
• Workpiece handling

Machine noise should therefore be evaluated from the complete operating cycle rather than from drive type alone.

For buyers comparing the two technologies, noise can be considered together with maintenance, energy consumption and hydraulic-system requirements when evaluating an electric press brake versus a hydraulic press brake.

Does Lower Noise Always Mean a Better Press Brake?

A lower measured noise value alone is not enough to determine overall press brake quality.

Noise can provide useful information about machine condition, but quality should also be evaluated through:

• Bending accuracy
• Repeatability
• Frame rigidity
• Hydraulic stability
• CNC control
• Safety system
• Tooling
• Backgauge performance
• Component selection
• Manufacturing quality
• Commissioning

A very quiet machine with poor bending accuracy is still a poor press brake.

Likewise, a large hydraulic press brake should not be judged against the same acoustic expectation as a small servo-electric machine without considering the test conditions.

The useful question is therefore not simply:

“How many dB is the machine?”

A better question is:

“Under which standard, operating condition and measurement method was this dB value obtained?”

What Should a Buyer Ask a Chinese Press Brake Manufacturer About Noise?

A useful noise specification should include the test basis rather than only one marketing number.

Before comparing suppliers, buyers can ask for:

• Applicable noise standard
• Machine transmission type
• Nominal force
• Sound pressure or sound power result
• No-load or loaded operating condition
• Measurement position
• Test method
• Factory inspection record, if available

For example, the following two statements do not provide the same level of information:

“Machine noise is 75 dB.”

and:

“A-weighted sound pressure was measured under continuous no-load operation according to the applicable factory test method.”

The second statement provides a much clearer basis for technical comparison.

Is GB/T 24388-2009 Mandatory for Chinese Press Brake Manufacturers?

GB/T 24388-2009 is currently a recommended national standard rather than a mandatory national standard.

The standard was originally published in 2009 and implemented in 2010. According to China’s national standards platform, it was converted to a recommended standard on March 23, 2017.

In practice, it remains a useful technical reference for press brake manufacturers, factory inspection and machine noise evaluation in China.

Buyers should therefore distinguish between:

a standard being technically used as an inspection reference

and

a standard being legally mandatory.

These are not the same thing.

Is GB/T 24388-2009 Still Current in 2026?

GB/T 24388-2009 remains the current published national standard for press brake and flanging-machine noise limits as of September 2026.

The standard was reviewed on May 22, 2026, with a conclusion that it should be revised, and revision project 20255234-T-604 is currently being drafted.

Until a replacement standard is formally published and implemented, GB/T 24388-2009 remains the current version.

For buyers using this article for future projects, it is therefore sensible to confirm the latest version of the standard when preparing contractual acceptance requirements.

Does Meeting the Chinese Noise Standard Mean a Press Brake Meets Export-Market Requirements?

Compliance with a Chinese factory noise reference does not automatically demonstrate compliance with every destination-market requirement.

GB/T 24388-2009 evaluates machine noise according to the Chinese press-brake standard framework.

Export markets may separately regulate:

• Machine noise declarations
• Workplace exposure
• Hearing protection
• Employer responsibilities
• Machine documentation
• Occupational safety

These requirements should be evaluated separately according to the destination country.

For an overseas buyer, GB/T 24388-2009 is therefore most useful for understanding how the machine itself may be inspected by a Chinese manufacturer before shipment.

It should not be presented as a replacement for local workplace regulations.

What Is the Practical Value of GB/T 24388-2009 for Press Brake Buyers?

The main value of GB/T 24388-2009 is that it provides a defined technical basis for discussing machine noise instead of relying on vague claims such as “low noise.”

It allows a buyer and manufacturer to clarify:

• What type of noise is being measured
• Which machine category applies
• Which nominal-force range applies
• Whether the result is sound pressure or sound power
• Under what operating condition the test is performed
• Which measurement method is used

This makes supplier comparison more meaningful.

When requesting a press brake quotation, buyers who consider noise important can ask the manufacturer to identify the applicable test standard and explain how the machine will be evaluated during factory inspection.

---

Frequently Asked Questions

What is the Chinese noise standard for press brakes?

GB/T 24388-2009 is the current Chinese national standard covering noise limits for press brakes and flanging machines.

Is GB/T 24388-2009 mandatory?

No. It has been a recommended national standard since March 2017, although it remains widely useful as a technical inspection reference.

What is the hydraulic press brake sound pressure limit?

Under GB/T 24388-2009, the limit depends on nominal force: 82, 85 or 88 dB(A) for the specified hydraulic-machine force ranges.

Is 85 dB(A) the limit for every press brake?

No. The applicable limit depends on machine type, nominal force, measurement type and operating condition.

What does LpA mean?

LpA means A-weighted sound pressure level measured at specified positions around the machine.

What does LWA mean?

LWA means A-weighted sound power level and describes the machine’s acoustic emission as a source.

Are press brake noise tests performed under load?

The main limits in GB/T 24388-2009 are specified for defined no-load operating conditions. Actual production noise may differ.

Is GB/T 24388-2009 being revised?

Yes. A revision project, 20255234-T-604, is currently being drafted, while GB/T 24388-2009 remains the current published standard.

---

Reference Standards

GB/T 24388-2009
Noise Limits for Press Brake and Flanging Machine

GB/T 23281-2009
Metal Forming Machinery — Noise Measurement Method of Sound Pressure Levels

GB/T 23282-2009
Metal Forming Machinery — Noise Measurement Method of Sound Power Levels