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Korea Aerospace Research Institute  Promising Technologies for Commercialization

Outline of Technology

TLO of the KARI

Person-in-charge

Senior Administrator Moon-Hee, Cho

E-mail : moonyxp@kari.re.kr
R&D Performance Diffusion Division 

Composite 
material 
Z-pinning

Technology of inserting pins in a thickness 

direction of a composite material laminated 

structure to prevent interlayer separation or 

strengthening a connection part by driving pins 

into a joint part when a plurality of composite 

material members are formed integrally.

Inventor

Principal Researcher Choi, Ik-Hyeon

Team

Material Structure Research Team

Status of right

• US : 9434110

• US /JP/CN : 8205654 / 2010-522655 / 101668633

Title

• METHOD  OF  MANUFACTURING  UNEVENNESS 

SHAPED Z-PIN AND Z-PIN MANUFACTURED USING 

THE SAME AND COMPOSITE STRUCTURE INCLUD-

ING THE Z-PIN 

• COMPOSITE  LAMINATED  STRUCTURE  REIN-

FORCED By INSERTING PINS, A METHOD AND A AP-
PARATUS FOR MAKING THE SAME AND A METHOD 
FOR MAKING THE APPARATUS 

Technical features and 

advantages

Distinctiveness
•  It does not cause any waste of materials, and a 

pre- and post-process of removing compressed 
foam before and after molding, and projecting 

pins is not necessary.

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Production of confirmed parts/system and prototype

Technical Readiness Level

TRL 1

TRL 2

TRL 3

TRL 5

TRL 6

TRL 7

TRL 8

TRL 9

TRL 4

Technical effects
• Since little influence is given to a 

process of manufacturing current 

composite materials, immediately 
applicable in industrial fields.

• Upon comparison with drilling work 

and use of metal fasteners, insertion 
of an automated Z-pin can achieve a 
70% reduction on manufacturing costs.

Technical features and advantages

Technical detail

This technology is in a state in which a sample product has been manufactured, 
and has been applied to manufacturing of small vessels in Korea.

Tension Fatigue Test Results for Joint Part

•  Static tensile test results for unevenness shaped pin single-lap shear joint
   -  Pin having a diameter of 0.5 mm, made of stainless steel, and having a pin density of 2.2% (an 

interval of 3 mm) and 4.9% (an interval of 2 mm).

   -  According to the joint part having a thickness of 6 to 8 mm, static strength is increased by 54 to 69%.
•  Tensile test results for unevenness shaped pin single-lap shear joint part
   -  Pin having a diameter of 0.5 mm, made of stainless steel, and having a pin density of 2.2% (an 

interval of 3 mm) and 4.9% (an interval of 2 mm).

   -  Fatigue strength is improved by about 100%, and fatigue life is improved by 100 times.

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Market and future prospects

Composite 

material 

Z-pinning

• AZTEX applied this technology to connect the engine bay 

door to the air inlet duct of a rear fuselage for F/A-18 E/F 
Super Hornet instead of a titanium fastener, so that the cost 

was reduced by $83,000 per aircraft and the weight was 

reduced by 17 kg per aircraft.

•  Applied to the cargo door of C17 Globemaster and Boeing-

Sikorsky  RAH-66  Comanche.  X-CorTM  that  has  the 
sandwich structure to which the Z-pinning technology is 
applied is applied to the tail cone in UH60M Black Hawk, 

so that a weight is reduced by 21 kg per helicopter.

•  Examples of use for roll over bar of Formula 1 Racing Car

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Applications

• Carbon fiber/glass fiber composite materials are broadly used for light weight products that 

require higher specific stiffness/specific strength than metal such as aerospace/wind turbine blade/
boat/yacht/high speed train/automobile/sporting goods.

• For the purpose of use of metal pins such as stainless steel in Korea and broad use in various 

fields of manufacturing composite materials, research into Z-pinning patch/elastic pad concept 
has been conducted to be applied to the various fields of manufacturing composite materials.