What's the difference between carbon UD,3K,12K and 18K ?

3K

12K 

UD

18K

About carbon weave

The unidirectional material can be oriented at any angle in each layer to optimize stiffness, torsional stiffness, and impact strength. The issue is that the material is very strong along the direction of the fiber and very weak between the fibers. If the laminate is damaged, the resin alone is not enough to constrain the damage. This is where woven fabrics come in.

3K  weave carbon fiber features a 3k tow (3000 filliments per fiber)  almost 3K carbon is from T300 , and is a commonly selected fabric style, delivering uniform strength in both horizontal and vertical directions. As normal , it is used in appearance of rim or frame of bicycle. and weight of 3k is not too much different with UD or 12K weave in rim.

12K  weaves offer the signature appearance that is highly desirable for modern composite parts with great conformability and strength. This fabric is frequently used for structural applications, offering improved economics to fabricators when compared to multiple layers of lighter fabrics. 

and features as below

weave provides signature aesthetics and ease of use

• Used to quickly add bulk and strength
• Unmatched strength to weight ratio
• High Modulus for superior rigidity
• Fire resistant material
• Fatigue resistance for durable strength
• 
  

UD  , Call Unidirectional Carbon, almost it is used in structure inside of bicycle frame and rim .so it is main structural material . except the apparance most people think it is boring, the better features UD have all like high modulus,light weight ,better toughness. that is why the most bicycle frame without weave carbon.

18K weave has 18mm*18mm size  , In fact .it is mostly used in another sports name ice hockey that Bauer stick with 18K carbon . 18K fabrics are woven together with fibers running in two directions,over one fiber and under the next , it has 18000 fills one fiber,very high modulus so far . it addes more strength from two directions in same time. but the manufacturer's cost is higher than 3K /12K . Usually, you may find 18k carbon  in track bike disc wheel.