Drop-In Anchor
Flush Install, Solid Concrete Grip.
Threaded Anchor, Zero Surface Protrusion.
Factory Precision, Long Stable Fastening.
Drop-In Anchor | Flush Mount Concrete Fasteners Factory | Sinsun
Need drop-in anchors for overhead hanging or flush concrete fixings? Sinsun factory manufactures 1/4″ 3/8″ 1/2″ 5/8″ 3/4″ zinc & stainless steel drop-in anchors. ETA options. Bulk factory pricing. Global shipping.
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Drop-in anchor is also called an internal threaded concrete anchor, flush expansion anchor and female drop-in fastener.Designed for solid concrete and masonry substrates only, it is a precision deformation-controlled expansion fastener. This type of female anchor is assembled with an internal expander plug that can be installed quickly with a standard setting tool. Common mainstream specifications are 1/4 drop-in anchors, 3/8 drop-in anchors, 1/2 drop-in anchors and 3/4 drop-in anchors, covering light, medium and heavy duty concrete fixing projects completely. Ideal for projects requiring flat, clean wall finishes that yield flush surfaces following installation.
As a professional fastener manufacturer, Sinsun has optimized every detail of its drop-in anchors to differentiate them from common products on the market. Our drop-in anchors are made of carbon steel, zinc plated and stainless steel, all of which are thread rolled with precision and adhere strictly to dimensional tolerances.Our anchors feature thickened expansion tubes and a uniform plug expansion structure, providing a consistent locking force than generic models. We solve the problems of loose thread and insufficient expansion often seen in low-cost products. All batches are tensile and shear loaded and we can offer bespoke sizes and surface treatments for worldwide construction and industrial customers.
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| Anchor Size (Inch) | Thread Size (UNC) | Outside Diameter (Inch) | Drill Hole Diameter (Inch) | Anchor Length (Inch) | Min. Hole Depth (Inch) | Min. Embedment (Inch) |
|---|---|---|---|---|---|---|
| 1/4″ | 1/4‑20 | 3/8″ | 3/8″ | 1″ | 1″ | 1″ |
| 3/8″ | 3/8‑16 | 1/2″ | 1/2″ | 1‑9/16″ | 1‑9/16″ | 1‑9/16″ |
| 1/2″ | 1/2‑13 | 5/8″ | 5/8″ | 2″ | 2″ | 2″ |
| 5/8″ | 5/8‑11 | 7/8″ | 7/8″ | 2‑1/2″ | 2‑1/2″ | 2‑1/2″ |
| 3/4″ | 3/4‑10 | 1″ | 1″ | 3‑1/8″ | 3‑1/8″ | 3‑1/8″ |
Technical Specifications
Thread Type:National Coarse (UNC) for inch sizes; ISO metric for metric sizes
Internal thread depth:Approximately half the total anchor length
Setting requirement: Dedicated setting tool required for each diameter—using the wrong tool means incomplete expansion
Temperature range: –40°C to +100°C (carbon steel); –40°C to +400°C (stainless)
Approvals: Diamond point (sharp, reduces wood splitting during driving).
Raw Material: ETA‑22‑0912 / 0913 available for flanged metric versions
Approvals:120-240 nails per coil (industry-standard bulk packaging for efficiency).
Not for: Brick, hollow block, CMU, drywall, wood, or any soft substrate
Get A Quick Qoute| Thread Size | Drill Hole Diameter (mm) | Anchor Length (mm) | Min. Hole Depth (mm) | Recommended Torque (Nm) | Pull‑Out Load (kN) C20/25 Concrete |
|---|---|---|---|---|---|
| M6 | 10 | 25 | 30 | 8 | 2.7 |
| M8 | 12 | 30 | 40 | 15 | 3.3 |
| M10 | 14 | 40 | 50 | 17 | 5.0 |
| M12 | 16 | 50 | 55 | 35 | 7.6 |
| M16 | 20 | 60 | 65 | 60 | 10.2 |
Where You‘ll Actually Use -Drop‑In Anchors
1. Drop‑in anchor for overhead pipe hanging in concrete ceilings
You're in an elevator 30 feet up. The ceiling is concrete solid. It takes nearly 500 pounds of weight to suspend a 6 inch sprinkler main filled with water. The threaded rod has to go into the ceiling, but you don’t want it sticking out before you’re ready. This is solved with drop-in anchors. Drill the hole, set the anchor flush with the tool. Now you have an internal thread to receive your rod. Come back with the rod and thread it through. Hang your pipe. No drilling from underneath. None of that concrete dust in your face. We’ve supplied those for fire suppression systems, HVAC duct work and electrical cable trays on many commercial projects.
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2. Drop‑in anchor for heavy machinery footings in industrial floors
Factory floors get roughed up. Vibration from the stamping press. Lift truck impact loads. The problem with standard expansion anchors is that they can slowly loosen up when subjected to continuous shaking. As opposed to push-in anchors, drop-in anchors work differently, because the internal expansion cone permanently bonds the body to the hole walls. The anchor is down and it’s not sticking. These columns are commonly found in automotive and food processing plants for machine tool bases, conveyor line equipment, and heavy shelving.
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3. concrete stone and solid block in architectural
Stone cladding. SOLID BLOCK RETAINING WALLS - Existing concrete walls with decorative bollards added. The rule is simple: a drop-in anchor is effective if the substrate is solid and cured. But here's a tip - if you're working with stone or block that may have an inconsistent density, use a knurled stainless steel drop-in anchor. The knurling grips the wall of a hole better than a smooth body. We’ve supplied these for marble panels in hotel lobbies, solid block bases for park benches and concrete light bollards along city walkways.
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4. electrical panel and transformer mounting
Electrical rooms are restricted areas. Transformers are heavy. Meters and switchgear must be attached to concrete walls without drilling through the other side. A 1/2” drop-in anchor has the holding power of a wedge anchor, but is completely flush. Doesn’t interfere with panel doors. No exposed threads to catch a technician's sleeves. Electrical contractors like them because they can pre-set all their anchor points before the panels even get on site. .
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Step 1 - Drill hole.
Use a hammer drill and a carbide tipped bit the same size as the anchor's outside diameter. That's a 3/8" bit for a 1/4" drop-in anchor. For 3/8” drop-ins. Use 1/2”. Drill perpendicular to the surface. Do not wobble the drill, reaming out the hole wider than spec kills holding power.read more -
Step 2 – Get the depth right.
The hole must be the same depth as the length of the anchor. The anchor is flush with the concrete surface when fully installed. Mark your drill bit with tape at the right depth. For a 2 inch long 1/2” drop‑in anchor drill 2 inches deep.read more -
Step 3 – Clean the hole well.
Use compressed air to blow away the dust. Clean the sidewalls with a nylon brush. Vacuum if available. Dust is the enemy of friction, and friction keeps a drop-in anchor in place.read more -
Step 4 – Set the anchor.
Drop the anchor into the hole, threaded the end up. Tap it lightly so that the top is flush with, or just below, the concrete surface.read more -
Step 5 – Tighten the anchor with the correct tool.
Screw the dedicated setting tool into the opening. Smash the tool with a hammer. When the tool is fully set, the tool shoulder should be in contact with the top of the anchor. You will feel the expansion. Anchors will not expand without a setting tool.read more -
Step 6 – Thread your bolt or rod.
Now the anchor is ready for threaded hardware. Insert your bolt or threaded rod and torque to the recommended specs. Do not over-tighten as excessive torque can strip internal threads.read more
| Substrate | Best Anchor Type | Drop‑In Suitable? | Why / Why Not |
|---|---|---|---|
| Solid concrete (overhead) | Drop‑in anchor | YES | Flush mount. No protruding hardware. Internal threads ready for rod. |
| Solid concrete (floor / wall) | Wedge anchor or drop‑in | YES | Wedge for permanent high load; drop‑in if you need to remove the bolt later. |
| Cracked concrete | ETA‑rated drop‑in or chemical anchor | YES (with ETA approval) | Standard drop‑ins not rated for cracked concrete. Request our ETA‑rated flanged version. |
| Brick or solid block | Sleeve anchor | NO | Drop‑in anchors require dense, uniform concrete to expand against. Brick varies too much. |
| Hollow block / CMU | Toggle bolt or hollow wall anchor | NO | No solid material for internal expansion. Drop‑in will spin. |
| Drywall / plasterboard | Toggle bolt or molly bolt | NO | Drop‑in anchors do NOT work in drywall. The substrate has no compressive strength. |
| Outdoor / marine | Stainless steel drop‑in | YES | 304 for general outdoor. 316 for saltwater exposure. |
| High vibration environment | Drop‑in (knurled) or epoxy | YES (knurled) | Knurled body resists rotational loosening better than smooth body. |
What Our Customers Are Saying
Drop-in anchors enjoy steady high demand in Middle East, Central Asia and Southern Europe markets. We select authentic long-term cooperation feedback from three core regions to display real product performance:
“
“We were installing fire sprinkler risers in a 12‑story office tower. Overhead concrete deck, 3/8” drop‑in anchors, threaded rod hanging pipe. First we tried a competitor‘s anchors—five out of a hundred spun when we torqued them. Switched to Sinsun. Not one failure across 450 anchors. My guys stopped re‑drilling holes. That’s a week saved on the schedule.”
“
“Coastal project in Abu Dhabi. Everything rusts within six months if it‘s not marine grade. We ordered stainless steel drop‑in anchors from Sinsun—1/2″ and 5/8“ sizes. Two years later, I walked the site. No corrosion. The setting tools still fit perfectly. We’ve placed three repeat orders since.”"
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“Our steel fabricator in Poland recommended Sinsun after a bad batch from another supplier. We needed M12 drop‑in anchors for column base plates on a warehouse mezzanine. The embedment depth was tight—only 55mm available in the floor slab. Sinsun‘s metric anchors matched our spec exactly. No oversize holes. No loose fits. The structural engineer signed off on the first inspection.”
Frequently Asked Questions
Q: What is a drop-in anchor?
A: Overhead thread rods. Female anchor points flush mount on concrete floors and ceilings. Anywhere you want a bolt hole that doesn't stick out above the surface.
Q:What size drill bit for a 3/8" drop‑in anchor?
A: 1/2” bit. The drill hole diameter is the anchor's outside diameter, not the internal thread size.
Q:Can you install a drop-in anchor in brick or hollow block?
A: No. Drop-in anchors are designed for solid concrete only. Brick and block are too inconsistent. Instead, use sleeve anchors or toggle bolts.
Q: What is the difference between a drop-in anchor and a wedge anchor?
A: Drop-in anchors are female anchors (internal threads) that sit flush to the surface. Wedge anchors are male anchors (threadened studs protruding from the surface) with an external expansion clip.
Q: Are stainless steel drop‑in anchors worth paying extra?
A: Yes, if moisture is present. 304 stainless steel is suitable for indoor humidification or occasional outdoor use. 316 stainless steel is suitable for coastal or chemical plant environments.
Q:How deep should the hole be for a drop-in anchor?
A:The anchor length is exactly. Drill 2 inches deep for a 2‑inch long 1/2” drop‑in anchor.
Q:Can I remove a drop-in anchor after setting?
A:Not if you want to damage the concrete. Permanent are drop‑in anchors. Internal expansion is not reverseable. Drill another hole next to it.
Q:What torque is needed for an M10 drop-in anchor?
A:17 Nm for carbon steel M10 in concrete C20/25. Look up the specific specs in our torque table above.
Q:Does Canon have ETA-certified drop-in anchors?
A:Sure. Our flanged metric drop-in anchors are ETA-22-0912 and ETA-22-0913 rated for cracked and non-cracked concrete applications.
Q:What is the load rating of a 1/2” drop-in anchor?
A:For standard carbon steel in non‑cracked concrete C20/25 with 2 inch embedment the pull‑out load is approximately 7.6 kN (760 kg). Contact us for the full data sheet for your project.
Q:Q: Do you have custom Sunsun thread sizes?
A: We stock standard UNC and metric threads. Custom runs are available in minimum quantities. Send us your drawing
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