Compression Limiters from SPIROL

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Compression Limiters are used to preserve a threaded joint’s integrity. As the bolt is tightened to achieve the required friction between threads, the plastic is compressed.

Without a Compression Limiter, plastic will either crack or creep, resulting in the loosening and eventual failure of the joint.

The Compression Limiter absorbs the load when the bolt is tightened to its recommended value. The plastic is isolated from excessive compressive loads and plastic integrity is maintained – ensuring that the joint remains intact throughout the life of the product.

The SPIROL range of Compression Limiters includes: the Series CL220 Split Seam, Series CL200 Split Seam - Slim Profile, Series CL350 Split Seam - Heavy Wall, Series CL400 Split Seam - Oval and the Series CL500 Molded-In. Standard machined options include: the Series CL6000 knurled, CL6100 headed & CL620 general purpose aluminum and Series CL8000 knurled & CL8100 headed brass Compression Limiters.

Each type of Compression Limiter is designed to accommodate different compressive loads, positional tolerances and installation methods. All formed Compression Limiters, except the Series CL220, are zinc plated and have a supplementary coating of trivalent passivation and an organic sealant for corrosion resistance. This finish provides 144 hours to white corrosion, and 384 hours to red corrosion when salt spray tested in accordance with ASTM B117. SPIROL’s Series CL220 Compression Limiters are coated with ArmorGalv^®, a zinc alloy thermal diffusion coating that provides a minimum of 1000 hours corrosion resistance to red rust. Machined Limiters are manufactured from aluminum and brass, both of which have inherent corrosion resistant properties and thus do not require supplementary finishing.

Sereis CL220 Split Seam: The Series CL220 Compression Limiter is produced from high carbon steel and intended for post-mold installation. The spring force generated during installation provides self-retention in the assembly. The flexible diameter accommodates wide hole tolerances, and the gap is designed such that the parts will not interlock in the free state. Once installed, the CL220 provides a minimum clearance of 1mm around the bolt diameter to compensate for misalignment. The CL220 is the only standard Compression Limiter finished with a protective coating of ArmorGalv®, a zinc alloy thermal diffusion coating complimented with two sealers that provides 1000+ hours of salt spray protection for highly corrosive applications such as automotive, marine, mining and industrial manufacturing. Additional benefits of ArmorGalv® include no insignificant surfaces as the entire inner diameter (ID) of the Limiter receives full coating and protection. The CL220 is rated for use up to ISO Class 8.8 bolts. The CL220 offers the widest range of standard diameter and length combinations to accommodate a variety of application requirements.
Series CL200 Split Seam - Slim Profile: Similar to the Series CL220, the CL200 Slim Profile Compression Limiter has a smaller inner diameter (ID) after insertion and a reduced overall profile with less clearance around the bolt. Once installed, the CL200 provides a minimum clearance of 0.5mm as compared to the larger minimum clearance of 1mm provided by the CL220. The CL200 is rated for use up to ISO Class 8.8 bolts.
Series CL350 Split Seam - Heavy Wall: Similar to the Series CL200 Compression Limiter, the CL350’s were designed with a thicker wall for increased bearing surface when clamped against soft mating materials. Generous bolt clearance also aids in positional alignment when multiple Compression Limiters are used in an assembly. The CL350 is rated for use up to ISO Class 10.9 bolts.
Series CL400 Oval Press-In: Produced from high carbon steel, the oval Series CL400 accommodates up to 2.25mm extra clearance on one axis, providing additional flexibility over round Compression Limiters for centerline and stack-up tolerancing. Similar to the CL200 and CL350, this split-seam oval Limiter is roll-formed, and it is spring tension that provides positive retention in the hole. The roll-forming manufacturing method yields substantial cost savings over machined products with similar features and characteristics. The CL400 is rated for use up to ISO Class 8.8 bolts.
Series CL460 Oval Molded-In: The CL460 Series is similar to the oval Series CL400, but produced with a butted-seam so as to prevent plastic from entering the inner diameter during the molding process. This series also accommodates up to 2.25mm extra clearance on one axis. The CL460 is rated for use up to ISO Class 8.8 bolts.
Series CL500 Molded-In: The Series CL500 is produced from low carbon steel with a butted seam to prevent plastic from entering the inner diameter of the Compression Limiter during the molding process. This also provides an anti-rotation feature once in the assembly. The radial grooves provide axial retention. The CL500 is rated for use up to ISO Class 8.8/Grade 5 bolts.
Series CL6000 Precision Machined - Aluminum: The Series CL6000 is machined from 2024 aluminum as this grade provides the best combination of strength, corrosion resistance, machineability and cost. Additional advantages of aluminum are that it is lightweight (1/3 the weight of brass), it is 40% stronger than brass, and it is lead free. These Limiters can be molded in or pressed into the assembly. The precision machined ID tolerance allows proper seating on the core pin when molding into the assembly. When pressed into the assembly, they are designed with a pilot that allows the part to stand freely in the hole prior to completing the installation. Once installed, the knurl provides excellent retention within the hole. The CL6000 is rated for use up to ISO Class 10.9/Grade 8 bolts.
Series CL6100 Precision Machined - Headed Aluminum: The CL6100 headed aluminum Compression Limiter is the same as the CL6000, with the addition of a head. The head provides extra bearing surface on the mating component when a flanged bolt or a washer is not used.
Series CL8000 Precision Machined - Brass: The Series CL8000 is machined from 360 brass. Similar to the CL6000, the CL8000 can be molded in or pressed into an assembly. The applications for SPIROL’s brass and aluminum Compression Limiters are very similar, however to accommodate the same class/grade bolt, the brass Limiters have a larger wall thickness due to the material’s lower yield strength. While this increases the size and weight of the Limiter as compared to the CL6000, the thicker wall does provide more bearing surface for the mating component. The most common reason a designer may choose the CL8000 is for those applications that require a shift away from aluminum on the galvanic series chart to make the Limiter more noble. The CL8000 is rated for use up to ISO Class 10.9/Grade 8 bolts.
Series CL8100 Precision Machined - Headed Brass: The CL8100 headed brass Compression Limiters are the same as the CL8000 with the addition of a head. Similar to the CL6100, the head provides extra bearing surface on the mating component when a flanged bolt or a washer is not used.
Series CL620 General Purpose - Aluminum: The CL620 is designed for use in non-critical applications and industries with forgiving assembly requirements. Similar to the CL6000, the CL620 is manufactured from lightweight, lead-free aluminum, offered in a narrower size range with generous tolerances that enable highly efficient manufacturing. For applications that are highly automated with stringent tolerance requirements, or if a headed configuration is required, consider the standard CL6000/CL6100 lines.