Metal Spacers for Fastened Assemblies | Hebei Wotu Fastener Manufacturing Co., Ltd.
Metal spacers keep a defined gap between parts while transferring clamp load or supporting an assembly. The main purchase decision is the spacer's fit: choose its material, length, inside diameter and outside diameter around the fastener, mating parts and service environment.
For panels, brackets, circuit-board assemblies, guards and fabricated frames, the right spacer can prevent contact, keep holes aligned and control compression. A poor fit can leave excessive play, create uneven loading or cause the fastener to bottom out before the joint is secure.
Brand: Wotu Surface: zinc plated Specifications: in stock M8~M64 full standard specifications, covering precision, machinery, and steel structure full size range, supporting nonstandard tooth pitch and customized thickness Matching: Can be matched with bolts of corresponding specifications, flat washer, spring washer complete set of shipment Packing: packed in 25kg cartons and packed on wooden pallets.
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Brand: Wotu Surface: zinc plated Specifications: in stockM6/M8/M10/M12/M14/M16/M20 Chinese national standardfull range of specifications, support nonstandard thickness, tooth pitch customized Matching: can be matched with bolts of the same specification, flat washer, spring washer complete set of shipment Packaging: 25kg cartons, whole wooden pallets
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Brand: Hengzuan Surface: blue and white zinc plated Specifications: in stock ST2.9/ST3.5/ST4.2/ST4.8/ST5.5 Chinese national standard full series, complete rod length 13~60mm, supports nonstandard length customization; drilling adapts to steel sheet thickness 2~6mm Packaging: 25kg cartons, whole wooden pallets
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Brand: Hengzuan Surface: blue and white zinc plated, optional black oxide, color zinc plated coating Specifications: in stock 4.2/4.8/5.5/6.3mm wire diameter, length 16mm~165mm full size range, supports nonstandard customized rod length Packaging: 25kg export cartons, full-container wooden pallets wrapped with film, supports neutral packaging, private-label customization
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Brand: Hengzuan Surface: blue and white zinc plated, can be customized color zinc plated, black oxide plated Specifications: Comply with GB/T15856.2 Chinese national standard, in stock ST3.5/ST4.2/ST4.8/ST5.5 mainstream wire diameter, rod length 13mm~50mm full range of specifications, nonstandard length customization on demand, drilling applicable plate thickness 2~5mm Packaging: 25kg export cartons, full pallets wrapped with film, supports neutral export packaging, private-label customization
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Brand: Hengzuan Surface: Color zinc plated, optional blue-white zinc plated, black oxide treatment Specifications: Chinese national standard ST4.2/ST4.8/ST5.5 specifications, rod length 13~50mm in stock, supports nonstandard length customization Packaging: 25kg export cartons, full wooden pallets wrapped with film, supports neutral packaging, private-label customization
Read MoreMetal spacer selection points
Compare metal spacers by form, material, length, bore, outside diameter, thread arrangement, end-face quality and surface finish. The correct combination depends on the load path, fastener size, clearance around the joint and exposure to moisture, heat or dissimilar metals.
| Criterion | What To Check | Why It Matters | Buyer Tip |
|---|---|---|---|
| Spacer material and grade | Confirm the metal type, grade, and any required material documentation. | Material affects strength, corrosion resistance, weight, conductivity, and compatibility with adjoining parts. | Ask which metals and grades are available for your load and environmental conditions. |
| Outside diameter, inside diameter, and length | Compare the spacer drawing or sample against the bolt, shaft, and clearance available in the assembly. | A poor fit can create movement, interfere with fastener installation, or leave the joint improperly supported. | Provide the bolt size, required clearance, spacer length, and both diameters for confirmation. |
| Dimensional tolerance and end squareness | Request the applicable tolerances and confirm how the cut ends are finished and checked. | Length variation or angled ends can change clamping force and cause parts to sit unevenly. | Ask what tolerance is held on length and whether the ends are deburred and square. |
| Surface finish and corrosion protection | Verify whether the spacer is bare metal, plated, coated, or otherwise treated, and check compatibility with nearby materials. | The finish affects corrosion exposure, appearance, friction, and the risk of galvanic interaction in mixed-metal assemblies. | Describe the operating environment and ask which finish is suitable for contact with the mating parts. |
| Supply form and customization | Confirm whether the spacer is supplied as a standard sleeve, threaded standoff, shoulder spacer, or a custom part. | The wrong form can require extra washers, create alignment problems, or fail to provide the needed fastening function. | Send a simple drawing or assembly photo and ask which spacer form matches the installation. |
A plain spacer slips over a bolt or screw and sets the gap between two parts. A threaded spacer or standoff also provides an attachment point, so it suits assemblies that need repeated fastening or a fixed mounting height. A washer mainly spreads load under a fastener head or nut; it is not a substitute for a spacer when a controlled gap is required.
Material selection matters when the spacer touches dissimilar metals, moisture or heat. Confirm the required strength, corrosion resistance and electrical behaviour for the assembly rather than choosing by appearance alone. If the spacer is part of an insulated or electrically isolated assembly, confirm the complete joint design with the responsible engineer.
Start with the joint geometry. Specify the spacer length as the required separation between the parts, then check the inside diameter against the bolt or screw shank and the outside diameter against the available bearing area. Also confirm the fastener head, nut and tool can reach the joint without interference.
Match the material to the environment. Steel can suit general structural assemblies, while stainless steel or another corrosion-resistant option may be more appropriate for moisture exposure. When dissimilar metals meet, ask about galvanic compatibility and any required isolation. For repeated tightening, check that the material and finish can tolerate the expected clamping and service conditions.
Choose the construction for the job. Unthreaded sleeves are straightforward for through-bolted joints. Threaded standoffs are useful when one part needs to mount directly to the spacer, but their thread type, engagement and usable length must match the mating fastener. Check end faces, burrs and dimensional tolerances where alignment or a clean seating surface is important.
Prepare a clear enquiry. Send a drawing or dimensioned sketch with the spacer length, inside and outside diameters, material preference, thread details if needed, quantity and operating environment. Ask the supplier to confirm available tolerances, surface treatment and inspection information for the dimensions that affect your assembly.
| Criteria | Importance | Description | Example Options |
|---|---|---|---|
| Spacer form | Important because the form determines how the parts are fastened and serviced. | A plain sleeve suits a through-bolted joint, while a threaded standoff provides an integrated attachment point. | Use an unthreaded sleeve where one bolt passes through both components; consider a threaded standoff where a cover mounts to a fixed support height. |
| Length and inside diameter | Critical for maintaining the intended gap and allowing the fastener to pass without excessive play. | Length sets the separation between parts. The bore should suit the fastener shank and the joint's alignment requirements. | A spacer for a clearance bolt needs enough bore clearance for assembly but not so much that the parts can shift noticeably. |
| Outside diameter and bearing area | Important where clamp load must be transferred without local deformation or unstable seating. | The outside diameter should fit the available area around the hole and provide a stable contact surface against the mating parts. | A bracket with limited material around its hole may require a smaller outside diameter, while a softer panel may benefit from a broader bearing area. |
| Material and environmental compatibility | Important for corrosion resistance, load performance and assemblies that contain dissimilar metals. | Compare steel, stainless steel and other suitable materials against moisture, heat, required strength and electrical-isolation needs. | A dry indoor frame and a moisture-exposed assembly may require different material or finish decisions even when their dimensions are identical. |
| Thread arrangement and dimensional control | Critical for repeatable mounting and reliable tightening in threaded designs. | Confirm thread type, usable engagement, end-face condition, burr control and tolerances for dimensions that affect alignment or seating. | A threaded standoff must provide enough usable engagement for the mating fastener without allowing the fastener to bottom out before the joint is clamped. |
Related Options
For a panel, bracket or equipment assembly that must maintain a repeatable gap, give priority to dimensional consistency and clean seating faces. For a mounting standoff, give equal attention to thread compatibility and usable engagement so the fastener secures the parts without bottoming out.
The correct self-tapping roofing screw depends on the complete panel-and-substrate stack-up. Steel supports typically require a point and thread matched to the support thickness and any pilot-hole requirement; timber supports require a wood-appropriate thread and sufficient embedment. In both cases, buyers must define diameter, length, head, sealing washer, material or coating, environment, pull-out requirements, and […]
Direct answer: Choose a self-drilling screw when the fastener must create a hole through a verified metal stack before its threads engage. Choose a self-tapping screw when the assembly already has a correctly sized pilot hole or when the selected thread is intended to form or cut into the specified substrate. The decision must also […]
Yes, a correctly sized spacer can maintain a fixed gap, support the clamping load and keep mating holes aligned in these assemblies. Confirm the load path, available bearing area, fastener size and required separation rather than selecting by application name alone.
Choose a plain spacer for a through-bolted joint where the fastener passes through the sleeve and both parts. Choose a threaded standoff when the spacer itself must provide an attachment point or mounting height; check thread type, engagement length and clearance to prevent the fastener from bottoming out.
Usually not. A washer spreads load under a fastener head or nut, while a spacer sets a defined distance between parts and can carry load along its length. A washer may still be needed with a spacer if the joint design requires additional load distribution.
Provide the required spacer length, inside diameter, outside diameter and quantity. Add the fastener or thread details, material preference, dimensional tolerances, surface-finish needs and operating environment if those factors affect fit or service life.
Select the material and finish according to moisture exposure, strength, temperature and contact with other metals. Ask the supplier to confirm galvanic-compatibility considerations and whether an insulating spacer or barrier is needed for the complete joint.
Please include the required spacer length, inside and outside diameters, and material or thread requirements. A drawing and the assembly environment will help clarify fit and corrosion considerations.
