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Helicoil Insert
FEATURES AND BENEFITS..
Heli-Coil inserts provide a positive means for protecting and strengthening tapped threads in any material. The unique design features
of the insert offer many benefits.
  • Stronger Assemblies
    Tapped threads are strengthened because the inherent flexibility of the insert provides a more balanced distribution of dynamic and static loads throughout the length of thread engagement. This flexibility also compensates for variation in lead and angle error allowing each coil to carry its share of the load.
  • Corrosion Resistance
    Under normal environmental conditions, Heli-Coil inserts minimize galvanic action within the threaded assembly because of their superior corrosion resistance.
  • Design Felxibility
    Bolt tensile strength can be balanced against parent material shear strength, assuring bolt failure rather than parent material damage. Five insert lengths are available in each thread size.
  • Eliminate Stress
    Virtually no stress is introduced into the parent material because there is no staking, locking, swaging or keying in place – the outward spring-like action of the insert holds it in place.
  • Minimize Space and Weight
    Heli-Coil inserts allow use of smaller bosses, flanges and fasteners than any other insert. Heli-Coil inserts can generally be incorporated in existing designs, where no provision has been made for an insert, without increasing boss size.
  • Minimize Total Cost
    Cost savings abound. Lower insert cost, lower installation cost and Heli-Coil inserts provide design flexibility by allowing a wide choice of parent materials while maintaining maximum threaded assembly strength.
  • True Clamping Torque
    Maximum clamping action and bolt tension are assured with minimum wrench torque because of the mirror-smooth surface finish of Heli-Coil inserts.
  • Wide Temprature Range
    Heli-Coil stainless steel inserts can be used in temperatures ranging from –320°F to +800°F.
  • Quality and Reliability
    Stringent Quality Assurance and Engineering Standards are rigidly enforced in all phases of the manufacturing process. This assures integrity of your product design.
High Production
Heli-Coil inserts are available mounted on plastic strips and wound onto reels (500 or 1000 inserts per reel). With power installation tooling, use of strip feed inserts will substantially increase installation rates by minimizing handling.
Universal Acceptance
Heli-Coil Standard and Screw-lock Inserts are the original – and have an extensive background of tension, torque, shear, vibration and fatigue tests conducted by American industry’s leading companies as well as the U.S. Military. Successful applications in the fields of aviation, electronics, industrial, automotive and military equipment provide a wealth of experience and confidence in the performance and reliability of Heli-Coil inserts.
Total Design Services
In addition to the benefits listed above, Heli-Coil provides a wide range of support to solve fastening problems. This manual is one of them
– the following pages are presented in a manner to make it easy to “design-in” Heli-Coil inserts to take advantage of the extraordinary
benefits they provide.

Additionally, our Sales Engineers, Applications Engineers and Design Engineers are available for consultation for specific designs. When the product gets to the manufacturing phase, our extensive experience in production tooling and installation techniques ensures that you can indeed make your product better with Heli-Coil inserts.
Helicoil screw locking thread inserts
Locking Features and Benefits..
Heli-Coil offers three types of Locking insert for multiple applications…
Screw Lock Inserts:
  • Positive self-locking torque, complying with NASM8846 and MA1565.
  • A resilient locking machanism (applies to Heli-Coil screw-lock inserts) that grips the bolt and prevents it from loosening under vibration or impact.
  • Repeated assembly and disassembly without appreciable loss of self-locking torque.
  • Saving in space, weight and money, through the elimination of lock wiring, lock nuts, lock washers, chemical compounds, plastic pellets/patches and other locking mechanisms.
High Torque Inserts:
  • Similer to Screw Lock except higher prevailing torque compensates for reduced friction in highly lubricated applications.
  • Ideal for higher vibration applications.
  • Approximate 40% increase in prevailing torque levels.
  • Available in #10 through 3/8" UNF only.
  • Meets AS1394, AS3094, 3095, 3096, 3097.
Stud Lock Inserts:
  • Highest prevailing torque insert available.
  • Enable use of threaded rod for space-saving stud applications.
  • Allows for any class fit of threaded rod.
  • Eliminates inconsistencies caused by interference fit studs.
  • Available for both straight and step studs, #10 through 1/2" UNC and UNF.
  • Meets AS1229, AS3080, 3081, 3082, 3083
Industry Standards
Heli-Coil inserts
and tooling comply with the following Standards and Specifications:
  • NASM122076 thru NASM122275.
    Insert, corrosion resistant Helical Coil Coarse Thread(Inch Series).
  • NASM124651 thru NASM124850.
    Insert, corrosion resistant Helical Coil Fine Thread (Inch Series)
  • NASM21209. Insert, Screw Thread - Self Locking (Inch Series)
  • NASM8846. Insert, Screw Thread, Helical Coil
  • MA1565. Insert, Screw Thread, Helical Coil (Metric Series)
  • MA1567. Insert, Screw Thread, Helical Coil (Metric Series), Standard Dimensions, Assembly
  • MA3279, 3280, 3281. Insert, Screw Thread, Helical Coil, Free Running(Metric Series)
  • MA3329,3330,3331. Insert, Screw Thread, Helical Coil, Screw Locking(Metric Series)
  • AS59158. Tools for inserting and extracting Helical Coil Inserts.
  • NAS1130. Insert, Screw Thread, Helical CoilFree Running and Screw Locking(Inch Series)
Helicoil Industry Standard
  • FED-STD-H28.Screw Thread Standard for Fedral/Services
  • AS1394 thru 3097
  • AS1229 thru 3083 Special Locking Torque Inserts
  • ASMEB18.29.1 Insert, Screw Thread, Helical Coil (Inch Series)
  • ASME B18.29.2M-2005 Helical Coil Screw Thread Inserts, Free Running and Screw Locking (Metric Series)
  • AGS3600-3699 Insert, Screw Thread, Screw Locking, Helical Coil, Cadmium Plated (Inch Series)
  • AGS4677 Series Insert, Screw Thread, Screw Locking, Helical Coil, Cadmium Plated (Metric Series)
  • AS6733 Inserts, Wire Thread, (UNF) - Unplated
  • AS6734 Inserts, Wire Thread, (UNC) - Unplated
  • AS8455 Inserts, Wire Thread, (UNF) - Cadmium Plated
  • AS8456 Inserts, Wire Thread, (UNC) - Cadmium Plated
Helicoil Insert coatings & plating
Coating/Plating Benefits
Dry Film Lubricant Provides additional lubrication in high friction applications High temperature resistance (400°F) Highly recommended with Heli-Coil Screw-Lock inserts Mildly corrosion resistant
Material Spec. AS5272 Color . Grey
Cadmium Plating Provides high corrosion resistance Provides lubrication to prevent galling (Not recommended for new design due to its toxic nature)
Material Spec. QQ-P-416-TYPE-II
Color: Iridescent yellow - Free-Running
Color: Olive drab - Screw-Lock
Primer - Free II Contains no chromates Free Eliminates need for zinc primers and epoxies Prevents galvanic corrosion between insert and parent material Eliminates locking torque issues associated with primers Improves installation productivity Provides additional lubrication facilitating insert installation
Material Spec:None
Color : Matte Black
Silver Plating Recommended to reduce galling of threads at high temperatures
For use up to 1200ºF
Color Coding Facilitates verification of insert installation Coding Allows for quick identification of similar size inserts
Available in blue, green, red, and black*
* All Heli-Coil Inch Screw-Lock inserts are supplied with a red coloring in accordance with NASM21209.
Helicoil insert Materials
Heli-Coil inserts are available in a wide choice of materials to suit specific application needs.
Contact Heli-Coil Applications Engineering to determine the correct material for your specific application.
  • Standard, General purpose material
  • Stocked in most size
  • Ideal for original equipment application, repair and overhaul.
Inconel v750
  • Used in areas exposed to high temperatures
  • Typical Uses : gas turbine engines, nuclear applications, well drilling
  • Non Magnetics.
Phosphor Bronze
  • Ideal for salt water application
  • Non magnetic
  • Exellent electrical conectivity
Nitronic 60
  • Superb gall resistance.
  • Compatible with stainless steel screws
  • Ideal for use in vacuum environment
  • Required no addional coating or Plating
  • Particle Free
  • non megratic
Titanium
  • suprior strength to weight ratio
  • Corrosion resistant
  • Excellent low temperature stability.
Helicoil screw lock torque data
Heli-Coil Screw-Lock inserts meet the locking torque value of Tables I and II shown below. The values shown conform to NASM8846 (inch
series) or MA1565 (metric series) requirement.
TABLE 1. Heli-coil Insert Locking Torque - Inch
Thread Size Max Locking Torque Min. Locking Torque 15th Cycle
INCH COARSE THREAD (UNC)
1(.073)-64 15 oz-in 2 oz-in
2(.086)-56 20 oz-in 3 oz-in
3(.099)-48 32 oz-in 7 oz-in
4(.112)-40 48 oz-in 10 oz-in
5(.125)-40 75 oz-in 13 oz-in
6(.138)-32 6 lb-in 1.0 lb-in
8(.164)-32 9 lb-in 1.5 lb-in
10(.190)-24 13 lb-in 2.0 lb-in
12(.216)-24* 24 lb-in 3.0 lb-in
1/4(.2500)-20 30 lb-in 4.5 lb-in
5/16(.3125)-18 60 lb-in 7.5 lb-in
3/8(.3750)-16 80 lb-in 12.0 lb-in
7/16(.4375)-14 100 lb-in 16.5 lb-in
1/2(.5000)-13 150 lb-in 24.0 lb-in
9/16(.5625)-12 200 lb-in 30.0 lb-in
5/8(.6250)-11 300 lb-in 40.0 lb-in
3/4(.7500)-10 400 lb-in 60.0 lb-in
7/8(.8750)-9 600 lb-in 82.0 lb-in
1(1.000)-8 800 lb-in 110.0 lb-in
1-1/8(1.1250)-7 900 lb-in 137.0 lb-in
1-1/4(1.2500)-7 1000 lb-in 165.0 lb-in
1-3/8(1.3750)-6 1150 lb-in 185.0 lb-in
1-1/2(1.5000)-6 1350 lb-in 210.0 lb-in
INCH FINE THREAD (UNF)
2(.086)-64 20 oz-in 3 oz-in
3(.099)-56 32 oz-in 7 oz-in
4(.112)-48 48 oz-in 10 oz-in
6(.138)-40 6 lb-in 1.0 lb-in
8(.164)-36 9 lb-in 1.5 lb-in
10(.190)-32 13 lb-in 2.0 lb-in
1/4(.2500)-28 30 lb-in 3.5 lb-in
5/16(.3125)-24 60 lb-in 6.5 lb-in
3/8(.3750)-24 80 lb-in 9.5 lb-in
7/16(.4375)-20 100 lb-in 14.0 lb-in
1/2(.5000)-20 150 lb-in 18.0 lb-in
9/16(.5625)-18 200 lb-in 24.0 lb-in
5/8(.6250)-18 300 lb-in 32.0 lb-in
3/4(.7500)-16 400 lb-in 50.0 lb-in
7/8(.8750)-14 600 lb-in 70.0 lb-in
1(1.000)-14* 800 lb-in 92.0 lb-in
1(1.000)-12 800 lb-in 90.0 lb-in
1-1/8(1.1250)-12 900 lb-in 117.0 lb-in
1-1/4(1.2500)-12 1000 lb-in 143.0 lb-in
1-3/8(1.3750)-12 1150 lb-in 165.0 lb-in
1-1/2(1.5000)-12 1350 lb-in 190.0 lb-in
TABLE II. Heli-Coil Insert Locking Torque – Metric
Thread Size Max. Locking Torque N.m Min. Locking Torque 15th Cycle N.m
METRIC COARSE
M2x0.4 0.12 0.003
M2.2X0.45 0.14 0.02
M2.5X0.45 0.22 0.06
M3X0.5 0.44 0.1
M3.5X0.6 0.68 0.12
M4X0.7 0.9 0.16
M5X0.8 1.6 0.3
M6X1 3 0.4
M7X1 4.4 0.6
M8X1.25 6 0.8
M10X1.5 10 1.4
M12X1.75 15 2.2
M14X2 23 3
M16X2 32 4.2
M18X2.5 42 5.5
M20X2.5 54 7
M22X2.5 70 9
M24X3 80 11.0
M27X3 95 12
M30X3.5 110 14
M33X3.5 125 16.0
M36X4 140 18.0
M39X4 150 20.0
METRIC FINE
M8X1 6 0.8
M10X1 10 1.4
M10X1.25 10 1.4
M12X1.25 15 2.2
M12X1.5 15 2.2
M14X1.5 23 3
M16X1.5 32 4.2
M18X1.5 42 5.5
M20X1.5 54 7
M22X1.5 70 9
M18X2 42 5.5
M20X2 54 7
M22X2 70 9
M24X2 80 11.0
M27X2 95 12
M30X2 110 14
M33X2 125 16.0
M36X2 140 18.0
M39X2 150 20.0
M36X3 140 18.0
M39X3 150 20.0
* These sizes are not included in NASM8846. Torque values shown are interpolated from sizes that are included. All torque data derived for stainless inserts only.
Helicoil Design Data
Assembly Strength
Heli-Coil offers maximum design flexibility while adhering to conservative engineering practice allowing use of Heli-Coil inserts in virtually any application or material. Five lengths of inserts are available. In this design manual, the lengths are listed as multiples of the nominal thread diameter of the screw 1,1.1,2,2-1/2, and 3.

This choice of insert length balances the bolt tensile strength against the shear strength of the parent material. This allows for the design of assemblies where the bolt will fail before the parent material. Tables III and IV below show the length of insert to be used with different combinations of bolts and parent materials
Shear strength of parent material(PSI)
(Alum.,Mag,Steel)
Table III - Inch Bolt & Heli-Coil Insert Selection Guide
Bolt Material Minimum Ultimate Tensile Strength(PSI)
54,000 75,000 96,000 108,000 125,000 132,000 160,000 180,000 220,000
10,000 2 2-1/2 3 3 - - - - -
15,000 1-1/2 1-1/2 2 2-1/2 2-1/2 3 3 -  
20,000 1 1-1/2 1-1/2 2 2 2 2-1/2 3 3
25,000 1 1 1-1/2 1-1/2 1-1/2 2 2 2-1/2 2-1/2
30,000 1 1 1 1-1/2 1-1/2 1-1/2 2 2 2-1/2
40,000 1 1 1 1 1 1-1/2 1-1/2 1-1/2 2
50,000 1 1 1 1 1 1 1 1-1/2 1-1/2
Shear strength of parent material(PSI)
(Alum.,Mag,Steel)
Table IV - Inch Bolt & Heli-Coil Insert Selection Guide
Bolt Material Minimum Ultimate Tensile Strength MPa(megapascals)
300 400 500 600 800 1000 1200 1400
70 1.5 2 2.5 2.5 - - - -
100 1 1.5 1.5 2 2.5 3 - -
150 1 1 1.5 1.5 2 2 2.5 3
200 1 1 1 1 1.5 1.5 1.5 2.5
250 1 1 1 1 1 1.5 1.5 2
300 1 1 1 1 1 1.5 1.5 1.5
350 1 1 1 1 1 1 1.5 1.5
 
Type of Conditions & Protective Methods
Parent Material Parent Material treatment Insert Treatment
Aluminum
Magnesium
Normal Severe Extremely Severe
None 1 1
1 1 1
Normal Severe Extremely Severe
None 2 or 3 2 or 3
None 2 or 3 2 or 3
Corrosion Protection Methods
Method 1 - Parent Material Protection
Aluminum: For oxide coating use Alodine, Anodize, Iridite, Hard Coat or equivalent. Iridite 14 or 14-2 (MIL-C-5541) is recommended for critical parts rather than anodizing (MIL-S-5002).

MAGNESIUM: For oxide coating use Iridite 15 or dichromate surface treatments. For HAE finishes, always plug tapped holes first.

Method 2 - Coat the insert with one of the following:
Cadmium per QQ-P-416, Type II, .0001" thick; or Dry Film Lubricant per AS5272 (MIL-L46010)(no graphite.)

Methode 3 - Utilize Heli-Coil Primer-Free II coated inserts or seprate the parent material from the insert by using liquid zinc chromate primer, Federal Specification TT-P-1757.Apply the primer to the hole sparingly and install the insert while the primer is still wet. In addition to the above methods, further corrosion protection can be achieved by:
  1. Using blind holes wherever possible.
  2. Using a sealing, insulating or step-down(5052 Alum.) washer under the head of the bolt.
  3. using bolts that extend completely through the length of the insert.
  4. In critical applications, using a non-harening sealer or compound on the threaded assembly.
helicoil, helicoil insert, helicoil inserts, heli-coil, , NASM21209,MS21209 ,NASM33537,MS33537 ,MS122076 to MS124831,NAS1130, LN9039,LN9039A, LN9499 ,LN9499A,DIN8140, MS122076 to MS124831,MA3279 ,MA3280 ,MA3281 ,MA3329 ,MA3330 ,MA3331, SAE8879, BACi12AE,AGS3600, AGS3700, AGS4677, AS6733, AS6734 , AS8455 ,AS8456 ,AS3094 AS3095,AS3096, AS3097, GE N926, N926A ,N926B ,N926C
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