Engineering selection / Tooling & stamping
Select springs for stripper plates, pressure pads and return mechanisms. Start with the installed length, actual spring travel and required loads at two working positions. Then check the JIS, ISO or US series, or request a spring made to your drawing or sample.
01 / Operating Condition Identification
First, describe the action the spring performs in the mechanism. The force stages for stripping, pressure holding, and returning differ; replacements for existing tools also require preserving the original assembly conditions.
The spring compresses during die closing and pushes the stripper plate during die opening. Verify the spring length and load at the start and end of stripping to ensure sufficient force is available during the required stages.
Commonly overlooked: Assuming the press slide stroke is the spring stroke, or only verifying the maximum force at die closure while neglecting the force during the die opening/stripping stage.
If documentation is incomplete: Provide partial tool drawings, spring installation photos, and the stripper plate travel first; mark load as "to be confirmed" if unknown, and retain the original model number or sample information.
The spring force differs when the pressure pad first contacts the workpiece and during subsequent compression. Describe the workpiece, pressure points, and the allowable force range, then verify the load variation in conjunction with the actual pressing process.
Commonly overlooked: Describing the modification goal as "stiffer" without specifying the initial force upon contact; or neglecting that increasing precompression will also change the closed die load and total compression.
If documentation is incomplete: First send a partial pressure pad drawing, workpiece condition, and the phenomenon you wish to improve; if force values are unavailable, provide the original model, assembly height, and closed die length as a starting point for verification.
The spring pushes the mechanism back to the target position as it releases compression. Selection requires verifying that the compression endpoint is within the working range and that the force near the end of return can meet the mechanism's needs.
Commonly overlooked: Selecting based solely on the maximum load at the shortest working position, neglecting the load decrease at the return endpoint; or directly equating the mechanism's travel with the spring compression.
If documentation is incomplete: First provide a video of the action or a schematic diagram of the mechanism, photos of the original spring, and a description of the position where it fails to reach, then supplement with assembly length, travel, and force requirements.
First, distinguish between periodic replacement, failure replacement, and performance modification. That the original spring fits does not mean that merely copying dimensions will restore the original load and working range; tool regrinding, stroke adjustments, and changes in operating frequency should also be noted.
Commonly overlooked: Assuming interchangeability based solely on color and appearance, or directly increasing the load rating upon encountering breakage without first checking total compression and guidance.
If documentation is incomplete: First send the original model, photos of the old part and installation, quantity, and reason for replacement; if the original model is missing, supplement with inner/outer diameter, unloaded length, and note whether the sample is intact.
02 / Length and Load
A spring may already be compressed when installed in the tool. The working stroke generated by continued mechanism movement must be added to this precompression. When verifying the catalog's allowable compression, do not compare only the mechanism stroke.
Dimensional Relationship Example · Not a Model Recommendation
Length of the spring when unloaded, used to define the starting point for compression.
Assembly precompression is 50 − 45 = 5 mm; assembly load is already present at this state.
Further compression of 10 mm; total compression relative to free length is 15 mm.
This example should be checked against the model using a total compression of 15 mm.
It only illustrates the length relationship and does not indicate that a particular spring model allows for 15 mm of compression. Allowable working compression, cycle conditions, and solid height must still be verified for the corresponding model. Solid height is the length at which the coils touch and cannot be used as the normal working endpoint.
03 / Engineering Selection
First confirm the dimensions fit within the space, then confirm the force and compression over the entire stroke. Color and load grade can be used to identify series, but specific models still require item-by-item verification.
Record the spring hole diameter, hole depth, guide rod diameter, assembled height, and end face structure. Distinguish between "spring measured outer/inner diameter" and "fitting hole/rod diameter"; the nominal installation dimensions in the catalog may not equal the actual spring size, and clearance must be confirmed according to the specific model requirements.
Mark the free length, assembled length, and minimum working length, and calculate the precompression and total compression separately. If the mechanism has levers, cams, or other drive structures, provide the actual movement at the spring location; do not directly apply the total stroke of the equipment.
At minimum, specify the load requirements at the assembled position and the minimum working position. Use units such as N, kgf, or lbf, and distinguish between single-unit load and load for the entire set; simply writing "heavy load" or "needs to be harder" is insufficient to confirm specifications.
Provide cycles per minute, daily operating time, maintenance intervals, and target service life requirements. The applicable range for the same model may differ under varying compression and cycling conditions; do not treat the limit values in the catalog as long-term working values for all conditions.
Confirm the fit between the guide rod or spring hole, guide length, support end face and parallelism, and check whether metal chips might enter the coils. Also verify the mechanism's minimum position and possible overtravel to keep the spring's actual operating range within the confirmed limits.
Confirm drawing version, dimensional tolerances, load and tolerance at specified length, material, and surface requirements. When lifespan or environmental verification is needed, agree on precompression, stroke, frequency, temperature, and acceptance criteria together to facilitate consistent standards for samples and subsequent batches.
04 / Standards & Replacement
Dingli die springs cover JIS, ISO, and US series. For replacements, retain the original model and catalog information, and compare dimensions, load capacity, and allowable compression in the same units.
When the drawing or original catalog specifies a JIS series
When the drawing or equipment specifies an ISO series
When the original equipment uses a US standard series
Color alone cannot be used as the basis for cross-series replacement.
The correspondence between color and load class may differ across series or manufacturers. Even if the color, outer diameter, and free length are identical, you should continue to compare the load at the specified length, allowable compression, guide fit, and end conditions.
When standard requirements or an original model exist, and dimensions, working load, stroke, and environment can be covered by a catalog model, first verify the standard series. Before ordering, record the complete model, quantity, and operating conditions.
When a standard model cannot simultaneously meet space, stroke, load, or material requirements, submit the assembly drawing and load points; if only a sample is available, also explain the actual application and existing issues to avoid merely replicating dimensions that are already worn or deformed.
05 / Troubleshooting
The following are the key clues to verify during communication. Breakage, length changes, and unstable action can be caused by multiple conditions simultaneously and cannot be determined solely from a single photo.
First, record: The breakage location, runtime or cycle count, condition of other springs in the same group, and whether the die has been ground, the stroke adjusted, or the stamping frequency increased recently.
Then verify: The total compression including precompression, operating range, guide friction, mounting end faces, and presence of foreign objects. Provide close-up photos of the fracture and wear areas, combined with actual operating conditions, to confirm if specification adjustments or assembly conditions are needed.
First, record: At which work position the problem occurs, whether it is consistent between cold start and continuous operation, and whether there is jamming or friction change.
Then verify: The spring length and load at that position, assembly precompression, number of springs and force distribution, and check the mechanism resistance. Before selecting a higher load grade, also review the total compression and structural load-bearing conditions.
First, record: The free length after unloading, the difference from a new part or the original drawing, and the distribution of the abrasion marks; retain a non-failed sample from the same group for comparison.
Then verify: Whether the operating range is exceeded, whether the end faces are misaligned, or whether the bore or guide rod is interfering. Do not alter die spring specifications by shortening coils or grinding inner/outer diameters; re-check the appropriate model or custom requirements instead.
First, record: The name, concentration, temperature, and duration of the liquid contact, and whether it has been rinsed, dried, or stored in a damp environment.
Then verify: Whether the base material and surface finish match the contact environment, and also check for mechanical scratches. When ordering replacements, specify the environmental conditions and appearance requirements; protective performance cannot be judged solely by coating color.
Replacements within the same load group should verify overall consistency. If new and old parts or different specifications are mixed, it is necessary to evaluate the force and load distribution of each spring at the same assembly length.
06 / Materials & Environment
Material grades, heat treatment, and surface finish serve different roles. First, specify the operating temperature, contact media, and cycling conditions, then verify the material selection; the specific materials for standard series are subject to the corresponding specification, and special material requirements are evaluated based on drawings.
07 / Sample & Acceptance
After the selection discussion, a verifiable specification record should be kept. Separate agreements on dimensions, load, and trial requirements facilitate that procurement, engineering, and both supply parties use the same documentation.
08 / Procurement FAQ
Please provide photos showing the side, end, markings, and mounting location first, and record the free length and inner/outer diameters. If the old part is broken, worn, or deformed, indicate the condition of the measured object. The original model, original drawing, or intact sample from the same set is more conducive to restoring the specifications.
Dimensions can be used for screening but are insufficient to confirm performance. First provide the original model or sample, assembled length, actual travel, and application. Clarify which load parameters remain to be confirmed, then supplement with design requirements or agree on a sample verification method.
You need to further verify the original series and specific model, and compare the load, allowable compression, and mounting fit at the same length. Color identification relies on the corresponding catalog; cross-standard or cross-manufacturer replacement cannot be judged solely by appearance.
Because the assembled height determines the precompression. The same working travel will result in different total compression and force ranges under different assembly precompressions, and will also affect the verification of the model's working range.
Service life is related to the model, precompression, working travel, frequency, temperature, guidance, and environment. When a life assessment or verification is required, these conditions and failure criteria should be clearly stated first. A single general cycle count cannot represent all installation conditions.
Specify the model or drawing, sample and batch quantity, delivery location, target lead time, as well as packaging, labeling, and inspection document requirements. The lead time, minimum order quantity, and inspection scope are confirmed based on specific specifications and the order.
09 / Inquiry Information
Dingli Spring supports standard die spring and custom manufacturing based on drawings or samples. Please send us the application, existing model or photos, installation dimensions, and quantity first; mark uncertain items as "to be confirmed," and we will verify them step-by-step based on operating conditions.
With photos only: First add dimensions and installation location. With sample: State if it is intact and its original operating conditions. With drawing: Include version and load points. In all three cases, specify quantity and target lead time.
Inquiry Email: jackchen@dinglispring.com
WhatsApp: +86 13586942004
Start with a drawing, an existing part number or photos of the old spring. Include quantities, target delivery and any parameters still to be confirmed.