FAQ | Mustika Rubberindo Naval Rubber Coupling Specialist

Frequently Asked Questions:

1. Fabrication / Repair / Refurbishment Price of Rubber Coupling

Competitive pricing compared to the market.
Price is negotiable with a maximum discount of 20%.
Price is determined by the specific item and type of rubber coupling.

2. Quality of Rubber Coupling Repair from Mustika Rubberindo

Proven and tested quality with numerous customers.
Quality backed by 15 years of repair experience.
Rubber quality is warrantied, ranging from 3 months to 1 year depending on the item’s size.

3. Rubber Coupling Material from Mustika Rubberindo

Uses a special Rubber Coupling compound custom-designed by Mustika Rubberindo.
Utilizes natural rubber material / Natural Rubber High Elastic Super Grade specifically for couplings.
Two material grades are available based on price: Grade A Super for direct end-users and Grade A Standard for resellers, who typically order based on a shorter service life for a lower price and faster transaction turnover.
Our rubber material is very strong against torsional loads from the engine, gearbox, and flywheel.
Our rubber material is resistant to engine room temperatures of 40 degrees Celsius.
Our rubber material has a strong and durable bond to the metal surface of the coupling.
Our material has been tested for 10-15 years with no issues reported from any users/customers.
A material to be avoided for rubber couplings is NBR rubber. NBR is only intended for use in machine components like seals, etc. While NBR material is heat resistant up to 80 degrees, its elastic strength is very minimal, making it unsuitable for rubber coupling applications. Based on our analysis, using NBR typically results in a short service life and rapid failure.

4. Rubber Coupling Repair Process

The lead time depends on the type of each rubber coupling item.
For 1 small rubber coupling (20 – 60 cm diameter), repair takes about 1 – 2 days for a complete circular dimension.
For 1 medium rubber coupling (60 cm – 100 cm diameter), repair takes about 1 – 3 days for a complete circular dimension.
For 1 large rubber coupling (100 cm – 130 cm diameter), repair takes about 3 – 5 days for both segmented and complete circular dimensions.

All the explanations above apply if we have the rubber coupling mold/matrix. Conversely, if there is a rubber coupling repair for which we do not yet have a mold, we will need to create the molding/matrix for that coupling, which will take 4 – 10 days depending on the size and type of the rubber coupling to be repaired.

5. Ordering Process for Rubber Coupling Repair

The user is asked for the type of Rubber Coupling, which can be identified from the brand symbol on the damaged coupling’s surface or from the ship’s manual, which usually specifies the type.
After we receive the item type from the user, we can check with Mustika Rubberindo whether a mold (matrix) is already available, as this affects the repair lead time. We can also ask the user if the request is urgent or for spare stock.
Alternatively, we can schedule a survey if the rubber coupling is not common in the market, allowing the Mustika Rubberindo team to analyze it and provide a price based on the analysis.

6. New Local Manufacturing of Rubber Coupling

Unbranded, with dimensions matching the sample.
Complete with metal and rubber.
The item matches the new or used sample provided.
Quality is nearly identical to the original.
Longer warranty compared to a repair.
Exact and precise dimensions.
A new manufacturing report document is provided.
A warranty certificate from Mustika Rubberindo is provided.
The color of the rubber coupling’s metal surface can be requested.
A video report of the balancing test and dimensional dial test can be provided.

7. Warranty for Repair or New Manufacturing

For repairs, the warranty corresponds to the grade of rubber ordered.
For Grade A Super material, the average warranty is 6 months.
For Grade A Standard material, the average warranty is 3 months.
For new local manufacturing, the warranty is 6 – 12 months, depending on the size of the rubber coupling.

8. Common Problems and Causes of Rubber Coupling Damage

Damage due to the quality of rubber repaired at a less-than-adequate workshop.
Damage caused intentionally or unintentionally by the ship’s crew, for example: a misaligned engine, improper shimming, or an incline between the gearbox and flywheel during installation, which leads to rapid wear of the rubber.
Damage due to operational force, such as when the ship’s propeller is maneuvered at low tide, causing it to strike mud or rocks, resulting in pressure, load, or torsional force that turns the engine. This makes the rubber coupling work under heavy, non-standard loads, causing the rubber to break or fail instantly.
Damage due to improper storage of a spare rubber coupling in a damp place, which can lead to mold and affect the rubber’s performance.
Damage when stock or spare parts are stored in an open area exposed to direct sunlight, causing the rubber to harden and degrade quickly, thus affecting its service life.

9. Pickup and Delivery Process

Typically, local users arrange their own cargo designated by them to be sent to Mustika Rubberindo’s address.
For users on Java island, items can be sent to Mustika Rubberindo by land via train or expedition services.
For users outside of Java, items can be sent to Mustika Rubberindo by land via expedition services or by air freight.
For local users in East Java, pickup can be assisted by the Mustika Rubberindo team.
After the repair is completed, shipping can be requested by the user, either by land or by air.