In our factory’s daily production, nails are small components that must be adapted to various uses. Round nails for construction must be able to withstand the pull of heavy objects, thin woodworking nails for furniture must not damage boards, and corrugated nails for fastening colored steel sheets must be non-slip. The differences between these nails all depend on the precise control of the nail making machine. Incorrect machine parameter adjustment or incorrect mold selection can lead to nails that are prone to breakage and reduced production efficiency, which can be frustrating. I’ve been in this business for nearly 10 years, and I’ve seen countless reworks due to operational errors. Today, I’ll break down various nail manufacturing techniques and teach you how to use machines to make high-quality, durable nails.
Preparation Before Production
No matter what kind of nails you make, you must do solid preparations before starting the machine, otherwise there will be problems during production.
Raw Materials Must be Selected and Processed Properly
Iron and steel wire are the main raw materials, and must be selected according to the type of nail:
For construction round nails and shooting nails, #45 high-carbon steel wire (diameter 2.5mm-6mm) is used. This steel is hard and durable. An apprentice once made a shooting nail by mistake using low-carbon steel and it broke when fired, but fortunately, no one was injured.
For thin woodworking nails for furniture, Q235 low-carbon steel wire (diameter 0.8mm-2mm) is sufficient. Its softness makes it easy to polish and less likely to damage the board.
For wavy nails, #35 medium-carbon steel wire (diameter 2mm-4mm) is selected. Its appropriate hardness allows for clear indentations and is less likely to break.
After receiving the raw materials, they must be pre-processed: a rust remover is used to completely remove surface rust (to prevent mold clogging). Then, when drawing the wire to the desired diameter using a wire drawing machine, care must be taken to avoid scratching the wire surface (to prevent a poor appearance of the finished nail).
Inspect the Machine Before Startup to Prevent Failures
Always inspect the machine’s main components before starting. Always check them in the following order: cutting → forming → twisting → power.
Cutting blades must be sharp. A chip on the cutting edge will result in uneven nail lengths. Previously, neglecting inspections and using a dull blade resulted in 20 out of 100 nails being out of spec, forcing reprocessing.
Forming dies must be tightly fitted, with a gap of 0.1 mm or less. Failure to do so will result in deformed nail heads. A previous dies was loose, resulting in distorted heads on round nails manufactured and resulting in customer returns.
Threading rotor grooves must be intact. Replace any excessive wear. Failure to do so will result in shallow grooves in the nail body and reduced clamping force.
Motor speed must be stable. Typically, it should be between 1400 r/min and 2800 r/min. Make sure the transmission belt is neither too loose nor too tight. A loose belt will slow down the rotation speed, while an overtight belt is prone to damage.
Prepare Tools and Consumables in Advance
Prepare necessary materials in advance to avoid shortages during production:
Prepare two sets of dies. For example, when making round nails, prepare an additional head die. If damaged, they can be quickly replaced without delaying production. Coat unused dies with anti-rust oil, otherwise, they will rust.
Choose L-CKC220 industrial gear oil for lubrication. Apply it to transmission parts to reduce wear. In the past, forgetting to refill the lubricant caused the machine to become abnormally noisy, and the motor almost burned out.
Inspection tools are also essential. Use calipers with 0.01mm accuracy to accurately measure length and diameter. Use a hardness tester and tensile tester to measure nail strength and avoid discovering non-conformances after product shipment.
Sort material boxes into “waiting inspection,” “passed,” and “failed” categories and do not mix them. In a previous case, a worker mixed rejected products into accepted boxes, resulting in a customer complaint and a large compensation payment.
Ensure Safety Protection Never Treat Safety Lightly
Because the machine operates at high speeds, safety is our top priority. I always remind my workers:
Always wear gloves, goggles, and non-slip shoes. One time, an apprentice wasn’t wearing goggles and a metal shard got into his eye. Fortunately, the problem was quickly addressed.
Remember the location of the emergency stop button. It’s a red button on the side of the machine. Press it immediately if an emergency occurs. We regularly conduct training to ensure that everyone can operate it.
Do not place any objects within one meter of the machine. Last time, there was some waste material there, and when a worker turned around, he tripped and nearly came into contact with the machine. It was extremely dangerous.
How to Make Different Nails
The production focus of each type of nail is different. Based on my usual operating experience, I have disassembled the operating methods of building round nails, furniture joinery nails, corrugated nails, and nail guns. They are all practical working skills.
Round Nails for Construction: Control Hardness and Size
The round nails for construction must be hard and accurate in size. I focus on the following points when adjusting the machine:
Choose the Right Mold and Install It Securely
The cutting die should be made of Cr12MoV material, with the hole diameter equal to the diameter of the wire. For example, for 3mm wire, use a die with a 3mm hole diameter, which will result in a flat cut surface.
To form the head, use a “round head, concave bottom” die, with a depth set 0.5mm greater than the height of the nail head (e.g., for a nail head height of 1.5mm, the die depth should be 2mm). This will ensure that the nail head is perfectly formed. When installing the die, be sure to secure it securely with a positioning pin. In the past, the die was not secured properly and shifted, resulting in all of the nails being bent.
There are Tips for Parameter Debugging
The cutting length is set based on customer requirements, typically 50mm, 75mm, or 100mm, with an error of no more than ±0.2mm. Typically, 10 test pieces are first cut and measured with a vernier caliper to confirm accuracy before mass production begins;
The punching pressure at the head must be sufficient. For high-carbon steel, this should be adjusted to 15MPa to 20MPa. In the past, there have been cases where the nail head came off when pulled due to insufficient pressure. However, the pressure was subsequently increased by 2MPa to meet the acceptable standards;
The appropriate wire feed speed is 1m/s to 1.5m/s. Dimensional accuracy deteriorates if the speed is too fast, while efficiency decreases if the speed is too slow.
Stay Careful in Thread Rolling
The surface of the round nail should have some texture to enhance grip:
Choose a fine-threaded threading wheel with a pitch of 0.5mm-0.8mm and a texture depth of 0.1mm-0.2mm;
Speed: 800-1000 rpm, pressure: 8MPa-10MPa. My last attempt at speed was too fast, and the texture wasn’t fully developed. I later reduced the speed to improve the results.
Trial Production is Critical
Make a trial run of 100 pieces first. During testing, focus on three key points:
Dimensions: Length and diameter tolerances must be within specified limits;
Hardness: Measured with a hardness tester, the HRB must be ≥85. If not, adjust the heat treatment temperature; quenching at 800°C-850°C is generally sufficient;
Firmness: When pulling the nail head using a tensile testing machine, it must be able to withstand a force of at least 500N. During one trial run, the hardness wasn’t high enough, so we raised the quenching temperature by 30°C and it met the standard.
Corrugated Nails: the Key Lies in the Grain and Tip Angle
The corrugated nails rely on the anti-slip texture and the tilted tip to fix them. These two problems must be solved during production.
Special Molds must be Installed Correctly
Choose a texture mold with spiral patterns, with a pitch of 1.5mm-2mm and a depth of 0.3mm-0.5mm. This provides excellent anti-slip properties. Previously, we used a mold with excessive pitch, and customers reported that the corrugated board tended to loosen.
The tip mold should be custom-made with a 30°-45° angle and made of wear-resistant WC-Co carbide. When assembling, install the texture mold first, then align the tip mold. Avoid centerline deviations exceeding 0.05mm, otherwise the pattern and tip will not align, affecting performance.
Multi-link Synchronous Debugging
The production of corrugated nails requires simultaneous cutting, corrugation, and tip forming. The following adjustments are typically made:
The PLC control system sets the operation interval to 0.2 seconds, allowing the corrugation to be formed immediately after cutting. This prevents the wire from shifting. There have been cases where setting the interval too long has resulted in the wire being distorted and the waveform becoming uneven.
The groove pressure is set to 15MPa to 18MPa. First, test 10 nails to check the clarity of the groove. If the pressure is insufficient, increase the pressure; if too much, decrease the pressure until the groove is clear and does not break.
The tip angle is measured with a goniometer. If there is an error of 5° or more, the die bolts should be adjusted. Previously, incorrect adjustments resulted in the tip becoming too sharp and piercing cardboard.
Don’t Produce too Fast
Corrugated nails have complex shapes, so the speed should be slowed down to 0.3m/s-0.5m/s.
Running too fast can easily cause the mold to jam. Last time, a worker, trying to speed things up, increased the speed, causing the mold to jam. It took half an hour to fix the problem.
Stop the machine and inspect the mold every 500 pieces. Replace the mold if it’s severely worn; don’t wait until you’ve already finished a batch to discover it.
Strength Testing is Essential
To ensure the corrugated nails are strong, I always perform two tests:
Bending resistance: Using a testing machine, I apply a 300N lateral force. If the bend exceeds 10°, it fails and the hardness of the raw material or the punching force must be adjusted.
Grain adhesion: I use pliers to pull at the grain. If the grain breaks, I apply more pressure. For each batch of 1,000 sheets, I randomly select 20 for testing. Only those that pass the test are delivered.
Precautions for Making Different Nails
After working on different nails for a long time, I have summarized some special precautions, which are usually easy to overlook but very important points:
Adjust Operation by Hardness
High-hardness nails (construction nails/shooting nails): Inspect the mold every 2,000 nails and replace them if the cutting blade wears out beyond 0.1 mm. Measure the hardness of the raw materials. Last time, the 45# steel was not hard enough, and the nails produced were prone to bending, forcing us to re-procure the material.
Low-hardness nails (furniture nails): Press pressure should not exceed 12 MPa. Lithium-based grease is applied to the mold to reduce friction. In some cases, scratches occurred on the nail body when grease was not applied, requiring re-grinding.
Special Shape Nails
Due to the unique shape of wavy nails and nails, at least three prototypes are made before production:
First: Check the integrity of the shape (e.g., whether the grooves of the wavy nails are formed correctly, whether the tail structure of the nails is correct)
Second: Adjust parameters and measure accuracy (e.g., whether dimensions and angles meet standards)
Third: Make 100 prototypes to check stability. If there are no problems, proceed to mass production. In the past, there have been cases where insufficient prototypes were made before mass production resulted in inappropriate tip angles for wavy nails, resulting in mass waste.
Batch Production Needs to be Monitored
Regular round nails are sampled once every 1,000 pieces, and special nails are sampled once every 500 pieces, and The dimensions, hardness, and strength are measured. If any problems are found, the parameters are adjusted immediately.
A production log is kept, recording the raw materials, parameters, and inspection results for each lot. This will enable the cause to be identified quickly the next time a similar problem occurs.
Equipment Maintenance should be Timely
After cutting large diameter nails, clean the cutting mechanism of any chips; otherwise, it will clog when cutting small diameter nails next.
After cutting small-diameter nails, generously oil the forming mechanism. Small diameter dies are more susceptible to wear.
