Pressure Gauge Hairsprings: A Specification Checklist
A useful pressure gauge hairspring inquiry explains how the part fits the movement and what torque it must provide under defined conditions. A photograph can help identify the general shape, but a drawing and an agreed specification give the supplier a clearer basis for quotation.
You do not need to know every parameter before making contact. Separate the requirements you already know from the details that still need review. The following checklist can help you prepare that first discussion.
1. Identify the part and drawing revision
State that you need a hairspring for a pressure gauge movement. Include the existing part reference, drawing number and revision if available. If the inquiry concerns a replacement, explain whether the original specification must be reproduced or a design change is being considered.
A movement drawing or assembly photograph can show where the spring is installed. Mark the relevant component rather than relying on the gauge's pressure range to identify it. The dial range alone is not a complete hairspring specification.
2. Show the dimensions that affect assembly
For a flat-strip hairspring, provide strip thickness and width as separate dimensions. Also identify coil outer diameter, inner opening, number of turns and any required spacing.
If the part includes a collet, specify its bore, outside diameter and height. Show the inner and outer end forms, attachment positions, bends and mounting dimensions. Define the viewing direction when describing clockwise or counterclockwise winding.
State whether dimensions refer to the free spring or its installed condition. Mark critical dimensions and their tolerances on the drawing; a single general tolerance may not describe every assembly requirement.
3. Specify torque with its measurement conditions
A torque value needs a unit, a rotation angle and a reference position. Include the permitted tolerance and explain whether the reading is taken from the free position or from an installed, preloaded position.
Where relevant, identify the direction of rotation, measurement temperature and loading or unloading sequence. If torque is checked at several angles, list those points and their acceptance limits. Ask the supplier to review the proposed test method before comparing results.
Avoid sending an unlabelled number or using pressure, force and torque as interchangeable quantities.
4. Describe the material and operating environment
If the original design specifies an alloy grade and temper, include both. If you only know the material family, say so. A supplier should be able to distinguish a confirmed requirement from a material preference.
Describe the temperature and any relevant exposure at the spring's installed location. If electrical or magnetic requirements apply, include them explicitly.
Material appearance is not a reliable substitute for a material specification. Our hairspring material selection guide explains the information needed to discuss common material families.
5. Explain the order and acceptance requirements
Separate the initial sample quantity, first production order and estimated repeat demand. Give your requested delivery date without assuming it is already agreed.
Identify the inspection records, packaging protection and part identification you need. If a particular test or acceptance procedure is required, include its conditions and limits in the inquiry rather than assuming it is included in every quotation.
Before placing an order, confirm which drawing revision, specifications and acceptance requirements apply.
A practical inquiry checklist
You can copy the following fields into your inquiry:
- Application and movement reference:
- Drawing number and revision:
- Material grade and temper, if known:
- Strip thickness and width:
- Coil dimensions and number of turns:
- Collet and end attachment details:
- Torque, unit, test angle and reference position:
- Torque and dimensional tolerances:
- Operating conditions:
- Sample and production quantities:
- Inspection, packaging and delivery requirements:
If a field is unknown, write “to be reviewed” and explain what information or sample is available. That is more useful than guessing a value.
For product information, see our pressure gauge hairsprings. To discuss a quotation with Kunshan Xintao, send the available drawing or sample details and identify any open questions.