Basic information about rotary dampers
Q: Why do lids and doors close slowly when using rotary dampers?
A: Rotary dampers contain oil inside, and when the shaft connected to the lid or door rotates, the oil is stirred or flows through a narrow passage,
causing the oil’s viscosity (stickiness) to act as resistance, thereby slowly moving the lid or door.
Related Articles: トイレのスローダウン機能とは｜なぜ蓋がゆっくりと閉まるのか
ロータリーダンパーとは？
Q: What are the main materials used in rotary dampers?
A: We use resins (POM, PBT, PA, etc.), zinc die-castings, silicone oil, and other materials.
Resins and die-castings are materials that can be mass-produced in complex shapes by making molds, making them ideal for rotary damper parts.
Additionally, resin is relatively lightweight and offers the advantage of being able to select from various types to meet requirements such as chemical resistance and heat resistance.
Since rotary dampers utilize the viscosity of oil, silicone oil is essential, and the oil viscosity is selected according to the damper torque.
Q: How should I choose a rotary damper?
A: Broadly speaking, you should choose based on usage, torque, and size.
Usage refers to how the lid is closed, such as horizontally or vertically, and the type of rotary damper you choose will vary depending on how the lid closes.
Torque is determined by the shape and weight of the lid, while size refers to the physical dimensions of the rotary damper.
The higher the required torque, the larger the rotary damper that should be selected.
Related Articles: ロータリーダンパーの選定方法
Q: Is there a limit to the rotation angle?
A: Partial rotation angle dampers have a limit on the rotation angle.
Partial rotation angle dampers have a structure where a partition is installed inside the rotary damper, and oil is flowed through a narrow passage to achieve high torque.
This partition causes the rotation angle limit.
Related Articles: ロータリーダンパー製品一覧
Usage environment
Q: Can it be used outdoors or in areas prone to salt damage (coastal areas)?
A: Basically, yes.
Rotary dampers are designed with rubber parts to seal the oil and prevent leaks, so they can be used outdoors.
Among the products in our catalog, those made of resin are susceptible to hydrolysis due to sunlight (ultraviolet rays), and those made of zinc die-cast are susceptible to white rust.
In both cases, measures such as avoiding direct sunlight and installing in locations where rain does not directly hit are recommended.
Q: Are there any rotary dampers that can be used below freezing?
A: Some rotary dampers have a proven track record of use in low-temperature environments,
but since viscosity changes depending on temperature, we recommend individual evaluation under severe conditions.
Durability
Q: Is it okay to apply direct load to the rotary damper?
A: Since the damper shaft is inserted into the center of rotation of the lid, the weight of the lid is applied to the rotary damper.
In the case of a lid that closes horizontally, the weight of the lid is applied when the lid is opened 90°.
At this time, it is preferable to design the rotary damper shaft to be inserted as deeply as possible into the lid.
Q: What happens if the torque exceeds the specifications?
A: If used at a torque higher than the rotary damper’s specifications, the damping torque will be insufficient, and the lid will not close slowly.
The greater the torque difference, the more the lid will close forcefully like a lid without a rotary damper,
and the rotary damper’s internal pressure will exceed the intended level, potentially causing component damage, oil leaks, and loss of normal functionality.
Q: Is it possible to use the product beyond the number of cycles specified in the catalog?
A: Depending on the conditions, there are cases where the product has been used beyond the specified number of cycles,
but such use is not covered by the warranty.
Please consult us separately for evaluation and verification based on long-term use.
Installation
Q: How do I install it?
A: Attach the damper housing to the fixed side (casing) and the shaft side to the movable part (lid or door).
It must be positioned appropriately relative to the center of rotation.
Related Articles: How to use rotary dampers | How to install on lids
Examples of rotary damper use and installation methods
Q: What are the requirements for installing a rotary damper?
A: A highly rigid structure with minimal deformation and deflection is required.
If the installation accuracy is low, the damper may not perform properly.
Functions and performance
Q: Is it possible to have a fast initial movement and a slow closing movement?
A: Yes, it is possible. Our rotary dampers are designed to slow down at the end of the closing cycle.
We can adjust the closing speed to some extent to meet your requirements, such as “slow at the beginning and fast at the end” or “slow only in the middle of the closing cycle.”
Q: Please tell me about the temperature characteristics and durability of rotary dampers.
A: Detailed data on temperature characteristics and durability is provided in the product catalog, so please check it.
Q: The lid does not close completely. Why is that?
A: There are two possible reasons why the lid does not close completely.
One is that a rotary damper suitable for the closing angle of the lid has not been selected,
and the other is that there is a discrepancy between the operating range of the lid and the operating angle range of the rotary damper.
In the former case, if a horizontal use rotary damper is used for a lid that hangs vertically in the closed position,
the damping will not work at first, and the lid will close very slowly, preventing it from closing completely.
In the latter case, if the rotary damper shaft cannot rotate any further before the lid reaches the closed position, the lid will not close.
Q: Which should I use, a rotary damper or a linear damper?
A: It depends on the purpose, but since linear dampers are visible when the lid is opened,
it is better to choose a rotary damper if you do not want them to be visible for design reasons.
Q: Are there any rotary dampers with torque adjustment functions?
A: Only TD27 and TD28 series are equipped with torque adjustment functions.
Customized rotary dampers with torque adjustment functions are also available.
Q: What is backlash in a rotary damper?
A: When switching from the open direction to the closed direction, there is some play before the damper starts to work.
This play is called backlash.
The amount of backlash depends on the presence of microscopic air pockets inside and the responsiveness of the internal parts.
Q: How can I reduce backlash?
A:
・Improve installation accuracy (reduce play and align the axis)
・Use multiple units to reduce torque (e.g., 2 N·m × 1 unit → 1 N·m × 2 units)
・Select a continuous rotation damper (viscous fluid is stirred in one direction, resulting in low backlash)
・Select a rotary damper with a large outer diameter (e.g., TD42 or TD89)
If the above measures do not improve the situation, we recommend consulting with us.
Q: Can the continuous rotation damper be rotated lightly in the opposite direction?
A: The continuous rotation damper has both bidirectional dampers and unidirectional dampers,
and the unidirectional dampers can be turned lightly in the opposite direction of the damper.
However, since the one-way mechanism is built into the oil-filled area (damper chamber),
there is some resistance from the oil seal and slight viscous resistance.
If lighter rotation is desired, a custom design can be made with the one-way mechanism outside the damper chamber,
reducing the idling torque to 3 mN·m (30 gf·cm) or less.
Customization
Q: Can the shape of the housing be changed?
A: Custom orders are possible provided that a mold is manufactured and the customer bears the cost of mold production.
The housing shape must be uniform in thickness to stabilize the degree of shrinkage during molding, so consultation is required.
Q: Can the opening angle be changed?
A: Yes, it can. We can accommodate this by changing the internal structure design.
Q: Are there any other examples of customized rotary dampers?
A: Please refer to the article on custom-made examples.
If you cannot find the rotary damper you are looking for, or if you need more detailed information, please feel free to contact us.
