Identify structural differences
Cutting holes and chip cavities are different features.
SELF-TAPPING INSERT · 307 / 337 / 307H
307/337/307H Blind-Hole Self-Tapping Inserts
Consider the blind hole and the chips.
Consider pilot-hole depth, cutting features and chip accommodation together. Similar model names do not imply the same chip-retention capability.
DESIGNED FOR CONNECTION
Include bottom clearance in your installation plan.
In comparable self-tapping designs, the cutting holes of type 307 differ from the chip cavities of type 337. A type 337 cavity provides space near the cutting zone for chips. A blind hole describes the parent material; it does not imply a closed-bottom insert or a chip-free installation.
Manage bottom clearance
Allow for the insert, screw and machining clearance together.
Assess cleaning requirements
Assess residual-chip control from the actual structure and validation results.
01 / STRUCTURE
Start with the right structure.
The insert structure determines how the 307/337/307H series connects and installs.
Type 307
Check cutting holes and effective length against the drawing.
Type 337
Check chip space and blind-hole clearance.
Type 307H
Confirm the suffix and structure against the ZCOIL drawing.
Related product:Explore the related product →
02 / MATERIAL
Match the material to the conditions.
These material options are discussion points; not every model is available in every combination.
Stainless steel
Confirm grade, strength and corrosion resistance against the supply drawing.
Other materials
Discuss the parent material, environment and connection loads.
Material documentation
Specify the material standard and required inspection documents in the order.
03 / SURFACE
The finish is part of the connection.
Consider friction, corrosion resistance and identification in the operating environment. Confirm available combinations with an engineer.
Surface condition
Confirm whether lubrication, protection or another treatment is needed.
Mating compatibility
Check the combination of parent material, screw, media and surface treatments.
Made to drawing
Include treatment type and thickness in dimensional and acceptance requirements.
INSTALLATION
From preparation to final inspection.
Check the section drawing
Confirm cutting holes, chip cavities and bottom geometry.
Prepare the blind hole
Check effective depth and bottom clearance.
Install to the approved procedure
Maintain alignment and prevent the insert from bottoming out too early.
Inspect residual chips
Inspect and clean according to the component's cleanliness requirements.
Type 337 references illustrate chip-cavity concepts only. No equivalence in dimensions, bottom geometry or performance is claimed for ZCOIL 307/337/307H products.
CONFIGURATION
Bring your requirements to our engineers.
Choose a preferred configuration and add thread size and operating conditions. This is an engineering enquiry, not a confirmed supply configuration.
Confirm these details for a clearer discussion.
Model differences
Confirm the structures of 307, 337 and 307H separately.
Effective depth
Check hole depth, insert length and screw length separately.
Chip accommodation
Confirm the cross-section; the label "blind-hole type" is not sufficient.
Cleaning and sealing
Specify each requirement separately; they are not interchangeable.
KNOWLEDGE & RESOURCES
Explore further.
Frequently asked questions
Does a blind-hole insert always have a closed bottom?
Not necessarily. A blind hole in the parent material, a chip cavity and a closed-bottom insert are different features.
Can both 307 and 337 inserts be guaranteed to retain all chips?
No general guarantee can be made. Check the actual structure and cleanliness validation; do not apply another brand's model description.