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Follow-up Inquiry and Request for Polishing Pre-Treatment Formula

  • 1.  Follow-up Inquiry and Request for Polishing Pre-Treatment Formula

    Posted 12 days ago
    Hi Scott,

    I hope this email finds you well. Firstly, I would like to express my sincere gratitude for your professional response to my initial query. Your insights were invaluable.

    I apologize for the delay in my follow-up; it has been quite some time since I last checked my emails. During this period, I have taken the opportunity to delve deeper into the practices of several world-renowned contract manufacturers. Their expertise has been enlightening.

    One persistent question I have revolves around the use of acid etching as a standard pre-polishing treatment. Specifically, I am curious about the suitability of hydrofluoric acid and nitric acid (Kroll's reagent) for this purpose. Could you kindly share your thoughts on this matter?

    Additionally, some research suggests that utilizing a blue oxide layer for intracardiac devices provides excellent stability. However, within blood vessels, corrosion becomes a concern. This discrepancy may be attributed to differences in tissue composition between cardiac muscle and vascular tissue.

    Lastly, I would greatly appreciate it if you could recommend a reliable pre-polishing chemical pickling/etching acid etching formula. Your expertise would be invaluable in our pursuit of optimal results.

    Best regards,
    Max Zhang

    R&D Manager | M.SC
    Cell: +86 15068867877
    Add: 4F, Bldg 5, Lan500, Furonghua Rd, Shanghai, China

    发件人: Scott Robertson via ASM International <>
    发送时间: 2024年3月9日 下午 1:28
    收件人: <>
    主题: RE: SMST Member Community : Is Sandblasting Essential for Making Nitinol Stents?

    SMST Member Community

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    Re: Is Sandblasting Essential for Making Nitinol Stents?
    Reply to Group Reply to Sender
    Mar 9, 2024 12:27 AM
    Scott Robertson

    Hi Max

    Most implantable braided nitinol devices are manufactured to remove thermal oxides created during the component forming operation. There are notable exceptions such as Abbott's Amplatzer line of occluders or Acandis's neurovascular devices. If you determine that your braided stent needs to have the thermal oxides removed to render it biocompatible, then sandblasting is certainly one option, but not the only one. Other common mechanisms for removing thermal oxide are chemical pickling/etching or tumbling. Any of these techniques can be employed as a precursor to a polishing operation. 

    The main challenge with both oxide removal and polishing of braided stents is the vast number of wire crossover points that serve as masked regions which can create non-uniform surfaces. Each oxide removal technique and braid pattern requires different strategies for uniformly removing the oxide and performing the subsequent polishing operation. This challenge is one of the very reasons why some designs like the ones mentioned above have chosen to forego the oxide removal step altogether.

    Best of luck!

    Scott Robertson

    VP, Nitinol Technology


    Scott Robertson
    VP - Nitinol Technology
    San Francisco CA
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