What information do you need to quote a custom hydraulic cylinder?

Send bore diameter, rod diameter, stroke, retracted (pin-to-pin) length, working pressure, single- or double-acting design, mounting type at both ends, port size and thread standard, operating environment and estimated annual quantity. A drawing, a sample or a photo of the original nameplate shortens the quotation process.

Can you reproduce an OEM replacement cylinder from a sample?

Yes. Our engineers measure the sample, prepare a technical drawing and send it for your confirmation before machining starts, so interchangeability is agreed in writing before production.

Which standards do your parts and tooling follow?

We machine to the customer drawing in metric or imperial units. Typical references include ISO 6H thread tolerance for hydraulic cylinder nuts, DIN 69872 and JIS B6339 for CNC retention knobs, and ER collet systems for milling tool holders.

Do you supply hydraulic cylinder components separately?

Yes. We supply cylinder heads, pistons, nuts, flanges, bases, integrated barrels, bushings and spherical bearings, as well as hydraulic valve blocks, for cylinder builders and repair workshops.

How are export orders packed and shipped?

Goods are packed with standard export materials to prevent transit damage and shipped by sea, air or express courier according to your preference, with tracking information provided.

How quickly will I receive a reply?

Our sales engineers reply to email enquiries within 24 hours. You can also reach the team directly by phone or WhatsApp.

JIS B6339 Retention Knob Pull Stud BT30 BT40 BT50 CNC Milling Tool Holder Accessories Wholesale Manufacturer Factory Supplier

Description

Material of retention knob is usually alloy steel such as 40Cr, 45# steel etc. JIS retention knob is a connecting component between machining centers and cutting tools, directly responsible for fixing the tools and withstanding high-intensity cutting forces. Their quality is related to machining accuracy and stability. Improper use can cause damage to the spindle or scrapping of the workpiece.

It is usually made of high-quality steel such as 20CrMnTi, and undergoes carburizing and quenching treatment. The surface is hard and wear-resistant, while the interior is tough. It has good fatigue resistance and can remain stable during high-speed processing.

According to the JIS B6339 standard, there is only one type of retention knob. The slope angle of the retention knob is 15 degrees and it is used in tensioning devices without steel balls, with the code "xxP".

Features

1. High Precision and Dimensional Stability

The dimensional accuracy and positional tolerance requirements are strict to ensure the precise fit with the tool holder and the spindle.

2. Mechanical Property Equilibrium

After targeted heat treatment, it possesses appropriate hardness and toughness, capable of withstanding tensile and impact forces during processing without becoming brittle due to excessive rigidity, balancing strength and fatigue resistance.

3. Reliable Consistency

In accordance with the production norms of JIS standards, the performance fluctuations of different batches of products are small, ensuring interchangeability and facilitating replacement and maintenance during mass production.

Parameters

Model No.	D	D1	D2	M	L	L1	L2	H	H1
LDJ-30P	12.5	8	12	M12	43	23.4	18.4	5	3
LDJ-35P	12.5	11	15	M12	44	24	19	5	3
LDJ-40P	17	14	19	M16	54	29	23	7	3
LDJ-45P	21	17	23	M20	60	30	23	7	4
LDJ-50P	25	21	28	M24	74	34	25	7	5
LDJ-55P	31	27	36	M30	98	48	36	11	7

Product Video

Packing

Service

Qingdao Micro Precision Machinery Co., Ltd. has been providing the following CNC tools services to global customers for decades.

Business Type: OEM & ODM Manufacturer
DRW Format Supported: DWG, PDF, IGS, STEP, SLDPRT, SLDDRW, PRT, DRW, DXF, X_T, etc.
Customization: Available upon reaching specified minimum order quantities
Quality Management System: ISO9001: 2008

Our Advantages:

Reliable Quality
Competitive Price
High precision & tight tolerance
Continuous Improvement
Defect-Free Products
On-Time Delivery
Customer Satisfaction
Excellent After-Sales Service

Frequently Asked Questions (FAQ)

Q1: What materials are commonly used for JIS retention knobs?

JIS retention knobs are typically manufactured from premium alloy steels such as 20CrMnTi, 40Cr, or 45# steel. These materials are treated with carburizing and quenching to ensure a wear-resistant exterior and a high-strength, impact-resistant interior.

Q2: What angle standard does the JIS B6339 retention knob follow?

According to the standard JIS B6339 specification, these retention knobs feature a 15-degree slope angle designed specifically for tensioning mechanisms without steel balls (designated with the "xxP" code).

Q3: Why is high precision so critical for pull studs?

Retention knobs are the mechanical connection between the tool holder and the CNC machine spindle. High dimensional accuracy prevents spindle runout, minimizes vibration during high-speed cutting, and protects the machine spindle from mechanical damage.

Q4: Can custom sizes or designs be produced?

Yes, custom retention knobs can be manufactured based on technical drawings or samples, provided standard minimum order volume requirements are met.

Q5: What file formats are accepted for custom manufacturing inquiries?

Engineering drawings can be submitted in standard industrial formats, including DWG, PDF, STEP, IGS, DXF, SLDPRT, SLDDRW, PRT, and X_T.

Q6: What quality control standards are applied during production?

Production processes strictly adhere to the ISO9001:2008 Quality Management System, ensuring rigorous inspection standards, dimensional stability, and consistent material performance from batch to batch.