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Getting to the ‘Heart’ of the Problem

Brief:

A Biomedical engineering customer set Northfield the following brief. To create chucks to hold heart valves, after coating, to finish grind. They were required to have multiple small internal grip collets and stops to allow fast tooling change over.

Challenge:

The small collet sizes and stop pads made this job unique. We were asked to hold the internal diameter of small multiple sized parts for a finish grinding operation. The internal diameters ranged from .305in (8mm) – .575in (14mm). We were also asked to locate datum that was inside the part on a small banking area.

The varying expansion range of the collet was an additional challenge. The customer part had a coating on it for which there was no set thickness. To solve this, we worked with the customers tolerance range and allowed the collets to expand approximately .040in (1mm) in diameter to allow for this coating variance.

Solution:

Three things were key:

1. Accuracy

2. Repeatability

3. Quick change over times

Our customer has many different part sizes and they wanted minimal down time when switching to a new setup. They could not be happier with the setup and are thrilled with how the project continues to produce accurate parts.

Do you have a unique working holding requirement? Then get in touch now. Our sales team are always available to answer your questions. https://www.northfield.com/contact/

 

About:

Northfield Precision Instrument Corp.: Northfield is a custom workholding solutions company based in Island Park, New York. Founded in 1952, Northfield designs and produces the most accurate custom chucks in the world, guaranteed from 0.0001″ (2.5µ) – 0.000010″ (0.25µ). Northfield supplies a global customer base across, automotive, aerospace and medical industries.

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Precision and Customization

Medical Engineering

Always looking for a chance to innovate, the Northfield team were excited to bring their years of work holding expertise to the medical industry creating parts for joint replacement.

Brief:

Achieve the appropriate tolerances requested. This included: concentricity, accuracy, and repeatability from part to part. We achieved this while allowing easy operation and quick tooling change over.

The Northfield team created two separate solutions:

  1. The first, develop a collet chuck solution to hold shoulder joint inserts to ‘finish-turn’ the outside.

Custom_Collet_Chuck

2. Secondly, holding multiple knee-joints simultaneously with a specific grip force. The customer required special clearance for milling tools and part sensing ports. These were designed allowing the machine to acknowledge when the parts are correctly loaded and ready to be manufactured.

custom_air_chucks

Challenge:

  1. Holding the half sphere shoulder parts from the inside with only a minimal surface area, to allow the finishing operation on the outside.
  2. The knee joints required custom air chucks to clamp various part sizes at the same time for finish milling.
  3. Ensure the correct jaw force was applied to the delicate parts throughout the entire process.

Solution:

  1. Northfield offers a large range of standard precision collet chucks, that grip a part internally. This job was unique as we developed a special contoured collet with a specific shape. Finish milled to enable holding several different part sizes. We also added a locating surface that uniquely has a small surface area, although robust and accurate enough to allow a long tooling lifetime.

2. Four different sized parts need to be held at the same time, therefore multiple Northfield chucks are in use simultaneously. Our customer wanted to finish the second operation of all the parts at once, achieved by creating a base plate with easy air porting.

3. Finally, we also delivered a force analyser that works together with our custom tooling, creating a turn-key solution with specific grip force.

 

Do you have a special working holding requirement? Our sales team are always available to answer your questions. https://www.northfield.com/contact/

Northfield is a custom work holding solutions company based in Island Park, New York.