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Paul M. Cook, Richard W. Muchmore · Public domain (expired patent)

أنشأه

22. سبتمبر 2026

Heat-Shrink Tubing

Paul Cook founded Raychem in 1957 to use radiation chemistry: electron beams that cross-link polyethylene chains so the plastic no longer melts, only softens. Such a material has a memory. Stretch it while hot, cool it stretched, and it keeps the new size until heated again - then it shrinks back tight onto whatever is inside. **US 3,086,242**, "Process and apparatus for producing materials having plastic memory", Cook and Muchmore, assigned to Raychem, filed 15. July 1960, granted 23. April 1963: tubing carried through a heated zone in a pressure vessel, expanded as it emerges, and cooled while expanded - "dimensionally heat-unstable tubing". **You measure the memory and use it**: free-shrink a sample and check where the plastic went, then insulate a crimped wire splice.

مبتدئ

1 hour

التعليمات

Measure as supplied

Cut 40 mm of 2:1 heat-shrink. Measure its flattened width, its wall (pinch one wall in the caliper) and its length.

المواد لهذه الخطوة:

أنبوب انكماش حراري1 قطعة

الأدوات المطلوبة:

سكين قصّ

قدمة رقمية 6 بوصات

Shrink it free

Hold it in the helping hands and heat evenly with the heat gun, keeping the gun moving, until it stops changing. Let it cool; measure inside diameter, wall and length again.

الأدوات المطلوبة:

مسدس هواء ساخن

اليد المساعدة

قدمة رقمية 6 بوصات

نظارة أمان شفافة

Crimp the splice

Slide 40 mm of heat-shrink onto one wire first. Strip 6 mm from both wire ends, push them into a butt splice and crimp each side. Tug each wire to 20 N on the spring scale - it must not pull out.

المواد لهذه الخطوة:

سلك توصيل1 متر

وصلة كبس غير معزولة1 قطعة

أنبوب انكماش حراري1 قطعة

الأدوات المطلوبة:

أداة تعرية الأسلاك

كمّاشة كبس الأطراف

مقياس قوة (ميزان زنبركي)

Shrink it on

Centre the tube over the splice with 10 mm overlap onto the insulation each side. Heat from the middle outwards so air is pushed out, not trapped.

الأدوات المطلوبة:

مسدس هواء ساخن

Test the insulation

Wrap aluminium foil tightly round the shrunk sleeve. Set the multimeter to its highest resistance range and measure between the wire and the foil: it must read open circuit. Then check the wire end to end: near zero ohms.

المواد لهذه الخطوة:

رقاقة ألمنيوم1 ورقة

الأدوات المطلوبة:

جهاز قياس متعدد

Shrink ratio and conservation

جارٍ تحميل دفتر Jupyter…

History & Context

**What the patent specifies:** tubing heated, expanded under pressure as it leaves a vessel, and cooled while expanded, to give material with plastic memory. **Modern build (derived):** commercial 2:1 polyolefin heat-shrink. Heat-shrink replaced tape on aircraft, military and then all wiring harnesses; the same memory idea gives shrink film and pipe-joint sleeves. Its limits: it must be slid on before the joint is made, overheating chars it, and a thin wall offers little protection from abrasion.