Kitagawa Standard Chuck Video explanation of how to calculate the specifications of the parallel movement chuck

09/07/2021

Akihiro Iwata

Engineering Advisor

After purchasing our standard chucks, we think there are many cases where customers design their own jaws. In that case, chuck specification calculation is necessary in order to use the chuck safely.

In this article, we will introduce how to check the following items as an approximate estimate.
1. Maximum allowable grip strength
2. Maximum rotation number
3. Grip strength loss due to centrifugal force

For approximate calculations, use the instruction manual that can be downloaded from each chuck product page on our website. Please refer to the graph on the page related to the center height of the gripping part, static grip strength, and input in the instruction manual.

▲From Kitagawa website

▲Graphs in the instruction manual

Before using the graphs, please check the following 4 points in advance.

1. Chuck model
2. Mass moment of the special jaws
3. Distance from the center of rotation of the chuck to the center of gravity of the special jaws
4. Height of gripping part

Specification calculation method using Kitagawa special jaws (for BB208)

This time, as an example, we will use the conditions described in the following figure to calculate the specifications.

▲Outline of the special jaws (for chuck model BB208)

1. Chuck model : BB208
2. Mass moment of the special jaw : 192kg・mm (according to the following formula)
3. istance from the center of rotation of the chuck to the center of gravity of the special jaw : 80 mm
4. Height of gripping part : 60 mm

Formula for calculating the mass moment of the special jaw
The mass moment of the special jaw (kg・mm)
= The jaw mass (kg) x the distance from the chuck center to the special jaw center of gravity (mm) × number of jaws

Calculating the maximum allowable grip strength and input

The value on the vertical axis indicated by the intersection of the gripping center height of 60mm and the grip strength limit line is the maximum allowable grip strength (60kN). The juncture of the intersection and the input-value curve is the input value (cylinder thrust) required to output a static grip strength of 60kN.

Calculating the maximum rotation speed

Extend the line of static grip strength shown in the graph on the right above to the graph on the left, and draw a line at the position of the mass moment of the special jaw calculated on the horizontal axis. The straight line of the rotation speed that passes through the intersection of these two lines is the maximum rotation speed (3700 min-1). The first line extended from the right graph represents the grip strength loss on the vertical axis. When the static grasp strength is 60kN and the rotation number is 3700min-1, the grip strength loss is 40kN.

Note: The maximum rotation number is the rotation number at which the grip strength loss becomes 2/3 of the static grip strength. 　　 Cutting resistance and other machining conditions are not taken into consideration.

The results obtained from the above graph are as follows.
1. Maximum static grip strength: 60kN (input: 23.5kN)
2. Maximum rotation speed: 3700min-1
3. Grip strength loss due to centrifugal force: 40kN
⇒ Dynamic grip strength: 60kN - 40kN = 20kN

The explanations given here are just the allowable specifications of the chuck itself. Please note that in actuality, design considerations must take into account the strength of the jaws and the machining load. Please feel free to contact us if you have any questions regarding the design of special jaws.

Last but not least, there is an indispensable lubricant called "CHUCK GREASE" for using chucks. The grip strength as calculated here can be maintained with daily maintenance.

We also recommend the use of CHUCK GREASE to ensure long and safe use.

If you are interested in Kitagawa (Thailand)'s machine tools (chucks, NC rotary tables, robot hands, etc.), please contact us using the form below.

Inquiry Form

Please feel free to contact us from the form as below.

We accept by phone and email.

Name Required

Company Name

Phone number

Email Required

Message Required

KOA-SHA (THAILAND) (hereinafter referred to as the "Company" or "We"), in the variety of services provided by the Company (hereinafter referred to as the "Services"), established the following privacy policy (hereinafter referred to as the "Policy").

Definition of Personal Information: The term "Personal Information" as used in this Policy, means information about a living individual which can identify the specific individual, including name, date of birth, and other descriptions (including other information that can be easily matched to identify a specific individual).

Acquisition of Personal Information: We acquire personal information by legally fair means.

Use of Personal Information

The Company shall use personal information for the purpose of business as necessary within the scope of the following.

To deliver optimized information to the individual user of the Service.
To help improve the quality of the Service by statistical analysis.
In response to inquiry in regard to the Service.
To conduct questionnaires regarding the Service.
To send information regarding campaigns and new products by the Company.
Other purposes associated with the abovementioned purposes of use.

About cookies: The Company makes use of cookies on the Service website. In addition, cookies may be used in a portion of the advertising system. A cookie is a small amount of data regarding usage history that is sent to your browser from a website’s server and is stored on the user’s hard drive. If the user prefers the Company not to make use of cookies, the user can set their browser to reject cookies. However, if the cookies are rejected, there is a possibility that the use of the Service on the website will be affected.

Provision of Information to Third Parties

The Company will not provide personal information to any third party without obtaining prior consent by the individual concerned, except as required by applicable laws and regulations.

In addition, the Company may access personal information and disclose it to third parties in the following cases.

Under Prior Consent of the Individual User Concerned
When the disclosure of personal information is required by law or judicial court, judicial orders, decisions and instructions based on laws and regulations of government agencies.
When reasonable measures are necessary to defend the rights or property of the Company.
When the disclosure of personal information is necessary to protect the lives, bodies or property of the Company, user(s), or public, and it is difficult to obtain the individual’s consent at the time.
When cooperation is necessary with a national or local government organization, or a business operator entrusted by such an organization in executing affairs under laws and regulations, and in which obtaining the consent of the user(s) is likely to impede the execution of the affairs.
In statistical data in which the disclosure or provision does not identify the user’s identity.

Management of Personal Information

The Company will maintain the accuracy of personal information and manage it safely.
The Company will take appropriate security measures to prevent the loss, destruction, tampering or leakage of personal information.
The Company will take precautionary measures against the loss, destruction, tampering, and leakage of personal information through appropriate system maintenance of the operating system and education of employees.

Request for Notification, Disclosure, Correction, Suspension of Use of Personal Information

In the case the Company receives request from the individual user regarding the disclosure, correction, addition, deletion, suspension of use, or erasure of personal information, stoppage of use by a third party or notification of use, after confirmation that the requester is the individual user, the Company will respond without delay in accordance with the Personal Data Protection Act.

Note that in the case that the request does not meet the requirements stipulated by the Personal Data Protection Act, or the reason to reject such request is permitted by the Personal Data Protection Act or other laws and regulations, the request may not be fulfilled.

In addition, there is no payment required or fees associated with the request for disclosure by the individual user. However, the cost of communication from the individual user to the Company, transportation expenses, and expenses associated with the preparation of materials for the purposes of individual identification will be the responsibility of the individual user.

Revision of Privacy Policy: The Company will review the operational status of the handling of personal information and make efforts for continuous improvement, and may change the Policy as necessary. After such changes to the Policy, the Policy will be published on the Company’s website.