Helical Insert Installation Guide & Common Tools Explained
- 翰君 陳
- Jan 2
- 4 min read
When repairing machines, installing equipment, or servicing parts, many people have run into this problem:No matter how you tighten the screw, it won’t hold—the threaded hole is stripped.
If you simply switch to a larger screw, it often affects the structure.If you re-tap the hole, it may not hold and can fail again quickly.
That’s when a Helical Insert becomes a practical and widely used solution.
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1. What Is a Helical Insert?
In Simple Terms: It Rebuilds a New Internal Thread Inside the Hole
A helical insert is a spring-shaped metal coil. After it’s installed, it forms a new internal thread inside the hole.
It’s most commonly used for three purposes:
Repair stripped threads when the original internal thread is damaged
Strengthen threads in soft materials like aluminum or plastics
Extend service life when screws need frequent removal and reinstallation
The benefit is that you don’t need to change the screw size, and you usually don’t need to remake the part.After repair, the thread often becomes more durable than the original.
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2. Why Does a Helical Insert Often Make the Thread More Durable?
The reason is simple.
A helical insert has elasticity. When the screw is tightened, the load is distributed across the entire insert, rather than being concentrated on a small section of the hole wall.
That’s why helical inserts work especially well for:
Softer materials like aluminum alloys and magnesium alloys
Cast iron parts
Plastic parts
Some stainless steel applications that require reinforced internal threads
However, if the hole wall is already very thin, or the structure must withstand extremely high loads, a helical insert may not be suitable—this should be evaluated in advance.
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3. Before Installation, You Must Confirm These Key Points
Many installation failures aren’t caused by bad inserts—they happen because the basics weren’t confirmed upfront.
Before installing, check:
Is the original thread metric or imperial?
Are the insert size and length correct?
Is the hole depth sufficient?
Is the hole wall thickness strong enough?
If any one of these is wrong, problems are very likely no matter how carefully you install later.
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4. How to Install a Helical Insert
First, Confirm Whether It’s a First-Time Install or a Replacement
In practice, the installation process differs depending on whether there is an existing insert in the hole.
Confirm your current condition, then follow the appropriate procedure.
Case 1: No Existing Insert (First-Time Installation)
This is the standard and most common workflow:
Drill → Tap → Install → Break Tang
Details:
Drill: Use the drill size specified for the insert. Do not reuse the drill size for the original screw.
Tap: Use a helical-insert tap to create the special internal thread for the insert (the insert’s external thread engagement).
Install: Use the installation tool to wind the insert into the hole. Typically, the insert is set slightly below the surface.
Break Tang: After installation, break off the tang at the bottom to prevent interference with the screw.
Case 2: An Old Insert Is Already Inside (Replacement / Rework)
If there is already an insert in the hole, remove it completely before reinstalling.
Workflow:
Remove → Drill → Tap → Install → Break Tang
Key reminders:
The old insert must be fully removed
Do not drill or tap on top of an existing insert
Skipping the removal step can easily cause misalignment or damaged threads, leading to poor holding strength.
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5. What Tools Do You Need for Installing Helical Inserts?
Whether you’re installing for the first time or replacing an old insert, these basic tools are commonly used:
Drill bitDrill the hole to the correct size required by the insert—select based on the insert specification.
Helical-insert tapUsed to create the thread form required for the insert. A standard tap for ordinary screws is not a direct substitute.
Note: “Tap” is the tool name, and “tapping” is the machining action—this refers to the same operation.Also, standard screw taps cannot replace insert taps, otherwise the insert may not seat properly or may loosen.
Helical insert installation toolDrives the insert into the hole in a stable manner. Choose manual or pneumatic tools depending on your use.
Tang break tool (or a punch)Breaks off the tang after installation so the screw can thread in normally.
Quick reminder: Different sizes and thread types require different drill sizes, taps, and installation tools. Always confirm all specs match before starting.
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6. When Are Helical Inserts Suitable—and When Are They Not?
Suitable cases:
The original thread is stripped
Aluminum or plastic parts need reinforced threads
The screw needs repeated assembly/disassembly
Not suitable cases:
The hole wall is too thin
The structure must withstand extremely high tensile loads
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7. If You’re Not Sure Which Helical Insert to Choose—What Should You Do?
Many people aren’t struggling with installation—they get stuck earlier because they’re unsure what to buy.
Common questions include:
Should this hole be metric or imperial?
Should I choose a short insert or a long insert?
Will an insert hold in this material—or will it fail?
Is buying inserts enough, or what tools do I also need?
If these points aren’t confirmed upfront, it’s easy to buy the wrong size, fail installation, or end up reworking the part.
Sheng Fong Precision can help you:
Confirm the correct metric vs. imperial specification
Select the correct insert size and length
Recommend the right tool set for installation
Avoid wrong purchases and wasted time/cost
LINE: @s9000Send us your specs, and we’ll help you get the selection right from the start.
🛒 Full Helical Insert Spec List: https://lihi3.me/9jPjQInsert Tap (Manual): https://shopee.tw/product/1024164764/28993797382/Insert Tap (Machine Use): https://shopee.tw/product/1024164764/54752938324/
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