{"product_id":"compression-springs-18mm-30mm-ballpoint-pen-spring-steel-galvanized","title":"Compression Springs 18mm-30mm Length Spring Steel Galvanized For Ballpoint Pens","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003eCompression Springs for Ballpoint Pens — Precision 0.4mm Wire, 18–30mm Length\u003c\/h2\u003e\n\u003cp\u003eWhen a ballpoint pen clicks but fails to retract smoothly, or a small mechanism loses its snap, the culprit is almost always a worn or undersized compression spring. Engineers, repair technicians, and DIY makers who need reliable, dimensionally consistent small springs will find these compression springs purpose-built for the task — delivering repeatable force in tight-tolerance assemblies.\u003c\/p\u003e\n\u003cp\u003eEach spring is wound from 0.4mm wire with an outer diameter ranging from 4mm to 4.5mm (approximately 0.157\" to 0.177\") and a free length of 18mm to 30mm (approximately 0.71\" to 1.18\"). Available in spring steel for maximum elasticity and fatigue resistance, or galvanized finish for added corrosion protection in humid environments.\u003c\/p\u003e\n\u003cp\u003eTypical applications include ballpoint pen retract mechanisms, small push-button assemblies, light-load valve returns, and precision instrument components — anywhere a compact compression spring for pen mechanisms or miniature spring replacement is required.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e🔧\u003c\/span\u003e \u003cstrong\u003eCompatibility:\u003c\/strong\u003e Designed for standard ballpoint pen cartridge housings and small-bore cylindrical seats with inner bore diameter ≥ 4.1mm. Verify free length and outer diameter against your assembly before ordering.\u003c\/div\u003e\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These Compression Springs for Ballpoint Pens\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cstrong\u003ePrecise Wire Diameter:\u003c\/strong\u003e Uniform 0.4mm wire gauge ensures consistent spring rate and reliable force output across every unit in the pack.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚙️\u003c\/span\u003e\u003cstrong\u003eTwo Material Options:\u003c\/strong\u003e Choose spring steel for superior elasticity and fatigue life, or galvanized for corrosion resistance in moisture-prone environments.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eMultiple Size Variants:\u003c\/strong\u003e Five size combinations (OD × Length: 4×20mm, 4×25mm, 4×30mm, 4.3×30mm, 4.5×18mm) cover a wide range of pen and small-mechanism applications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\u003cstrong\u003eFlexible Pack Quantities:\u003c\/strong\u003e Available in packs of 10, 20, 50, or 1000 — ideal for single repairs, prototyping runs, or bulk production restocking.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eConsistent Coil Geometry:\u003c\/strong\u003e Close-wound coil ends provide stable seating in cylindrical pockets, reducing lateral deflection during compression cycles.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🏭\u003c\/span\u003e\u003cstrong\u003eBroad Application Range:\u003c\/strong\u003e Suitable for ballpoint pen retract springs, push-button mechanisms, light-load valve returns, and other miniature compression spring applications.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — Compression Springs\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eWire Diameter\u003c\/th\u003e\n\u003ctd\u003e0.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter (OD)\u003c\/th\u003e\n\u003ctd\u003e4 mm \/ 4.3 mm \/ 4.5 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFree Length\u003c\/th\u003e\n\u003ctd\u003e18 mm \/ 20 mm \/ 25 mm \/ 30 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eSpring Steel \/ Galvanized Steel (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural (Spring Steel) \/ Zinc-plated Galvanized (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSpring Type\u003c\/th\u003e\n\u003ctd\u003eCompression (helical coil)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEnd Type\u003c\/th\u003e\n\u003ctd\u003eClose-wound \/ flat ends\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePack Quantity\u003c\/th\u003e\n\u003ctd\u003e10 \/ 20 \/ 50 \/ 1000 pcs (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSpring Rate\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMax Load\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-faq\"\u003e\n\u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I choose the right size compression spring for my ballpoint pen?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eMeasure the inner bore of your pen housing (the cylindrical seat where the spring sits) and the required free length when the pen is fully extended. The spring's outer diameter should be slightly smaller than the bore — for most standard ballpoint pens, the 4mm OD variants fit housings with an inner bore of approximately 4.1–4.5mm. Match the free length to the travel distance of your pen mechanism plus a small preload margin.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between spring steel and galvanized finish?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eSpring steel variants are made from high-carbon steel wire that is heat-treated for maximum elasticity and fatigue resistance — ideal for dry indoor applications where cycle life is the priority. Galvanized variants have a zinc coating applied to the steel wire, providing corrosion protection in humid or mildly wet environments. For standard pen use, either material works well; choose galvanized if the assembly may be exposed to moisture or sweat over time.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these springs suitable for applications other than ballpoint pens?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes. While sized for ballpoint pen retract mechanisms, these small compression springs are also used in push-button switches, light-load valve returns, precision instrument assemblies, hobby electronics enclosures, and miniature mechanical devices. Any application requiring a helical compression spring with 0.4mm wire, 4–4.5mm OD, and 18–30mm free length is a potential fit.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow strong are these compression springs — what load can they handle?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eDue to the small wire diameter (0.4mm) and compact coil geometry, these springs are designed for light-load applications — typically in the range of a few grams to a few hundred grams of force at working deflection. They are not intended for heavy-duty industrial clamping or high-force actuation. For exact spring rate and load data for a specific size, please contact us to confirm.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use these springs outdoors or in humid environments?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThe galvanized variants offer zinc-plated corrosion protection suitable for mildly humid or occasionally damp conditions. For prolonged outdoor exposure or contact with water, additional sealing or a stainless steel alternative may be more appropriate. The spring steel (uncoated) variants are best kept in dry indoor environments to prevent surface oxidation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhich pack size should I order?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eFor a single repair or prototype, the pack of 10 is the most economical entry point. If you are building a small batch of devices or want spares on hand, packs of 20 or 50 offer a lower per-unit cost. The 1000-piece pack is designed for production runs or resellers who need bulk compression spring stock at the lowest per-piece price.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo these springs meet any dimensional standards (e.g., DIN, ISO)?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThese springs are manufactured to match common ballpoint pen spring dimensions and are not explicitly certified to a specific DIN or ISO standard. If your application requires certified spring tolerances or traceable material certifications, please contact us before ordering so we can confirm suitability.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-cta\"\u003e🛒 Select your size, material, and pack quantity above, then add to cart.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"HomeDIYer","offers":[{"title":"0.4 x 4 x 20mm \/ Spring Steel \/ 10","offer_id":52449175437586,"sku":"GYWHLDLWJ00057x1","price":2.98,"currency_code":"USD","in_stock":true},{"title":"0.4 x 4 x 20mm \/ Galvanized \/ 10","offer_id":52449175470354,"sku":"GYWHLDLWJ00058x1","price":3.11,"currency_code":"USD","in_stock":true},{"title":"0.4 x 4 x 25mm \/ Spring Steel \/ 10","offer_id":52449175503122,"sku":"GYWHLDLWJ00059x1","price":2.98,"currency_code":"USD","in_stock":true},{"title":"0.4 x 4 x 25mm \/ Galvanized \/ 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