Radius Flank Thread Form for Thermoplastics
Benefits
Reduces radial stresses
Strong resistance to pull-out
High resistance to material stripping
Features
Unique Radius Flank thread form
Asymmetrical thread with thin angled tip
Wide pitched thread spacing
Designed for the Demanding Plastic Applications of Today and Tomorrow
The REMFORM® II™ screw is a thread-forming fastener with a unique thread form to provide superior performance in today’s wide range of plastics. The asymmetrical thread minimizes radial hoop stress to reduce boss bursting. The narrow tip angle also reduces stress on the plastic nut member.
REMFORM® II™ Screws For Plastic
Shown are typical applications suitable for REMFORM® II™ Screws.
Metric Series
|
SIZE |
PITCH |
MAJOR DIA. |
MINOR DIA. |
|
|---|---|---|---|---|
|
Max. |
Min. |
|||
|
1.0 |
0.55 |
1.07 |
1.00 |
0.64 |
|
1.2 |
.65 |
1.27 |
1.20 |
0.77 |
|
1.4 |
0.75 |
1.47 |
1.40 |
0.89 |
|
1.6 |
0.85 |
1.70 |
1.60 |
1.02 |
|
1.8 |
0.85 |
1.90 |
1.80 |
1.15 |
|
2.0 |
1.00 |
2.10 |
2.00 |
1.17 |
|
2.2 |
1.05 |
2.30 |
2.20 |
1.29 |
|
2.5 |
1.15 |
2.60 |
2.50 |
1.48 |
|
3.0 |
1.35 |
3.10 |
3.00 |
1.90 |
|
3.5 |
1.55 |
3.60 |
3.50 |
2.22 |
|
4.0 |
1.75 |
4.10 |
4.00 |
2.55 |
|
4.5 |
2.00 |
4.60 |
4.50 |
2.87 |
|
5.0 |
2.25 |
5.15 |
5.00 |
3.19 |
|
6.0 |
2.65 |
6.15 |
6.0 |
3.84 |
|
7.0 |
3.10 |
7.15 |
7.00 |
4.48 |
|
8.0 |
3.50 |
8.15 |
8.00 |
5.11 |
|
9.0 |
4.00 |
9.15 |
9.00 |
5.74 |
|
10.0 |
4.50 |
10.15 |
10.00 |
6.37 |
Inch Series
|
SIZE |
PITCH |
MAJOR DIA. |
MINOR DIA. |
|
|---|---|---|---|---|
|
Max. |
Min. |
|||
|
2 |
20 |
0.088 |
0.084 |
0.049 |
|
4 |
18 |
0.114 |
0.110 |
0.067 |
|
6 |
16 |
0.139 |
0.135 |
0.085 |
|
8 |
15 |
0.167 |
0.161 |
0.101 |
|
10 |
13 |
0.193 |
0.187 |
0.123 |
|
12 |
11 |
0.218 |
0.212 |
0.144 |
|
1/4 |
10 |
0.253 |
0.247 |
0.157 |
|
5/16 |
8 |
0.316 |
0.309 |
0.195 |
|
Material |
H |
|---|---|
|
PP |
0.75 |
|
PE |
0.75 |
|
PA (Nylon 6 / 6.6) |
0.75 |
|
ABS / PC Blend |
0.75 |
|
ASA |
0.75 |
|
ABS |
0.75 |
|
PVC (rigid) |
0.80 |
|
SAN |
0.80 |
|
PS |
0.80 |
|
PBT |
0.80 |
|
PET |
0.80 |
|
PC |
0.80 |
|
PPO |
0.80 |
|
PET 30% GF |
0.80 |
|
PC 30% GF |
0.82 |
|
PPO 30% GF |
0.82 |
|
PA 6 30% GF |
0.85 |
|
PBT 30% GF |
0.85 |
SUGGESTED BOSS CONFIGURATION
Hole sizes for the plastics listed in the table are derived by multiplying the minimum screw diameter by the factor listed in the table. The resulting hole size should be considered a starting point, which may need adjustment due to specific application conditions.
Reduced Hoop Stress
The radial tip thread crest of REMFORM® II™ screws reduces sharp corners, which reduces radial hoop stress in the plastic caused by thread forming.
When a threaded fastener is tightened, nearly all of the axial tightening load, designated F, is opposed by the trailing or pressure flank of the screw and the mating thread flank of the internal thread. The steep pressure flank transfers most of the resultant tightening load in the axial direction, Fa, minimizing boss bursting tendencies created by the radial force, Fr. The axial force, Fa, is over 4.5 times greater than Fr, the radial force.
The REMFORM® II™ asymmetrical Unique Radius Flank™ thread form has the thread-forming advantages of a 30° thread without the difficulty of manufacturing a 30° thread.
The Unique Radius Flank Thread™ Form
REMFORM® II™ screws employ the Unique Radius Flank™ asymmetrical thread form shown in the drawing to the right. The leading thread flank is most influential in forming the mating thread. The intercepting radius form on the leading flank is there to promote efficient material displacement and material flow. The pressure flank that opposes the fastener head is engineered to resist pull-out forces, whether applied by a tensile load or induced by torque. The steep pressure flank has a subtle radius designed to increase resistance to pullout and to efficiently develop tension. It also provides excellent material contact, resulting in a high resistance to the stripping of internal threads. In applications where the failure mode is fastener fracture, the high torsional strength of REMFORM® II™ fasteners ensures a high failure torque. This unique thread and its narrow tip angle efficiently displace material, requiring minimal energy to form an internal thread. The tip also utilizes a radius to create the internal thread without increasing hoop stress in the plastic.
Additional Family Products
For Magnesium, Aluminum & Reinforced Plastics
High Strength Thread Form for Thermoplastics
Data Sheet(s)
