MD and CD in Nonwovens — The Two Directions That Determine Strength and Uniformity
- dkfiber2004
- Oct 31
- 2 min read
Nonwoven is a sheet-type material made by bonding fibers physically or thermally without spinning or weaving processes. Interestingly, even when made from the same raw materials, its strength and elongation vary depending on the direction in which it is pulled.
At this point, two important reference terms are used: MD (Machine Direction) and CD (Cross Direction).
In this post, we will take a closer look at MD and CD.
MD (Machine Direction) – The direction along the production line flow
MD refers to the direction in which the nonwoven moves on the machine, aligning with the main flow of the entire production line such as carding, needle punching, and thermal pressing.
During the carding process, fibers are stretched along the rollers, which causes most of the fibers to orient in the MD direction.
Fibers aligned lengthwise → Tensile Strength ↑
Alignment is linear → Elongation ↓
Primarily influences structural stability and durability
Therefore, MD is considered the main load-bearing direction of nonwovens, serving as a key indicator of the product’s structural stability and durability.
CD (Cross Direction) – The direction perpendicular to fiber orientation
CD refers to the direction perpendicular to MD, meaning the crosswise (widthwise) direction of the nonwoven. In this direction, fibers are entangled more randomly, resulting in lower strength but higher elongation compared to MD.
Lower strength but greater deformation absorption capacity
Plays a key role in evaluating the uniformity and flexibility of nonwovens
In other words, CD (Cross Direction) is perpendicular to the fiber orientation. When pulled, the fibers are not aligned parallel to the tensile direction, making it harder for them to withstand loads, which is why the strength is relatively lower.
How is fiber orientation determined?
Most nonwovens form their web through the carding process, which naturally orients fibers in the MD direction. However, by modifying the process design, it is also possible to achieve fiber orientation in the CD direction.
Process Type | Fiber Orientation Characteristics | MD/CD Strength Ratio | Description |
Carding only | MD-oriented, one-way structure | 2:1 ~ 3:1 | Typical needle-punched nonwoven |
Carding + Cross Lapper | Cross orientation (±45°) | 1.2:1 ~ 1.5:1 | Balanced MD-CD structure |
Air-laid / Melt-blown | Random orientation | 1:1 | Isotropic structure |
In particular, cross lapper equipment stacks the web from the carding machine in multiple overlapping layers, alternating between MD and CD. This process enables the production of nonwovens with well-balanced physical properties.
Why is the balance between MD and CD important?
The performance of nonwovens is not determined solely by strength in a single direction.
The more balanced the strength between MD and CD, the more evenly the product maintains its dimensional stability, durability, processability, and compression recovery.
Category | Direction | Key Characteristics | Main Purpose |
MD | Production line direction | High strength ↑ / Low elongation ↓ | Load-bearing, enhances durability |
CD | Crosswise (width) direction | Low strength ↓ / High elongation ↑ | Ensures uniformity and flexibility |
The quality of nonwovens is determined not only by the type of raw material used but also by the design of fiber orientation (MD/CD) and the ratio of binder fibers.
MD direction governs strength and durability.
CD direction contributes to uniformity and flexibility.
The harmony between these two directions ultimately defines the completeness and performance of the final product.
