Ryuga Bonsai Tools: Processing and Quality Control

Post Production Durability QC Method (Japanese Standard)

Beside the material used, the processing method and skill, strict quality control is a must in bonsai tools production to ensure the functional quality, consistency and durability.

Beside functional quality, other common problems with bonsai tools is broken, or the least is causing an open gap on the blades. RYUGA fully aware and concern, and has full integrated system to ensure our functional quality, consistency and durability.

RYUGA is the only bonsai tools maker outside Japan using the reinforced 5Cr15MoV heavy duty steel, individually hand-made by skill workers with special heat and quenching process to achieve consistent hardness within the golden range of HRC56-58 which result high sharpness and strong durability.

RYUGA is the only bonsai tools maker outside Japan using the Post Production Durability QC Method, a standard method used by Japanese bonsai makers.

The Cause of Broken

Normally the broken section occurred between the cutting head and the handle, and this is due to the crystal structure of iron in the broken section which is called “Austenite residue” that still remained in the broken area. Actually in technical point, this area should not remain such rough “Austenite residue”, as “Austenite residue” has very bad deformability. In other word, if the iron of cutting head is very hard, “Austenite residue” would possibly cause brittle. We call this as being“Failure caused by Brittle”.

Another reason is in a heating treatment process for the “functional working part” to turn the iron form into high appropriate mechanical properties. This process should be done only limited on the “product working area” (not on the handles) as illustrated below.

Quality Control to Avoid Broken Problem

a. Initial check on the “raw pieces”. We do 100% hardness checks through the air pressing machine as below. Only the pieces that passed this test will be used for next production process.

Standard of air pressing: 60psi; 5Kg/cm2.

b. Based on our Japanese OEM partner’s standard request, we are using special formula alloy steel specifically used for bonsai tools. Our stainless steel material used is 5Cr15MoV with hardness reach to HRC56-58. The hardness of this alloy steel for bonsai tools is around 2 times than the normal steel used for garden tools.

General speaking, the higher is hardness is, the more brittle the alloy steel will be. Therefore, after initial air pressing hardness check, we still do a random check on some pieces to assure no “Austenite residue” inside by breaking the pieces.

c. After assembling the raw pieces, we conduct second air pressing testing to check if any crack occurred between joint areas after adjusting the balance between two cutting heads. This is also to check the hardness and flexibility of the handles; the handles should not bend after the test.

Standard of air pressing: 60psi; 5Kg/cm2.

d. After polishing the blades, we will conduct the final functional test by cutting a 15mm dry wooden stick to make sure the hardness and sharpness of the product before packing and shipment to the customers. Each tool must have made a clean cut on the dry wooden stick in one pressing without damaging the blades as to pass the final quality control.

Standard of air pressing: 50psi; 4Kg/cm2.

(Normally, 30psi; 2.5kg/cm2 of pressing power is enough to make the clean cut)

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Quality Control Method

On the initial production process of bonsai tools, the metal pieces should be properly forged by hand before casted into the shape. The forging process is the most crucial stage to ensure the density of the material, which later on confirms the final tool quality.

Another crucial stage is on the cold oil process to harden the blade part. Any pin holes due to improper forging process will severely affect the blade quality, which can cause broken. The problem is that there is no technique to ensure if the forging process has been done properly on the entire piece before the cold oil process; so a good quality control method is needed to confirm the final quality.

We are using Post Production Durability QC Method, a very high QC procedure as used by Japanese tools makers, to ensure our quality, both the consistency of material quality as well as the final functional quality and durability.
After the cold oil treatment, each piece of our tool will go through the pressing test to ensure the blade quality as shown on below picture.
Any improper forging process will never passed the process, the thinner parts will break....

Only the pieces that passed this process will go on to the further finishing process. But this is not the end...each piece will go to another pressing test to ensure the quality of the whole piece especially on the handles. The handles should not bend after the severe pressure...

Done ?..NO !
The final test should be the functional test...to cut dry wood to ensure the cutting result is clean sharp at the middle and the handles are not bending...

Any minor quality will cause the cutting result, or broken or causing an open gap on the blades...

The similar strict QC procedures are conducted on all "Ryuga" different model tools including our scissors before shipment. We give 2 years free replacement guarantee to all of our tools.