Humera Sankyo Corporation

Quality Assurance

Quality Assurance


Humera Sankyo Corporation stainless steel had tools are manufactured using a variety of corrosion resistant steels. “Corrosion-resistant”, however, is not synonymous with “rust-free forever” and a certain amount of care is required to maintain the tools’ original corrosion –resistant characteristics over the hand tool their use. Passivation of stainless steel is a process routinely used during the manufacture of our hand tools that produces a passive (i.e., non –reactive) oxide layer on the surface of the material, which protects the steel against corrosion. In addition to proper cleaning and care, additional Passivation cycles may be performed to remove stains and to extend the life of the tools. But no amount of attention after the fact can substitute for careful, preventative maintenance. Users should read and follow this maintenance guide in order to obtain the maximum use and benefit from our tools. 


All tools are shipped in a non-sterile condition and must be cleaned and sterilized before use. Distilled water is recommended for rinsing, as tap water can contain minerals that may stain or discolor the steel. If tap water is used, then the tool should be dried immediately to avoid staining. Do not use abrasive cleaners, which can scratch the surface and remove the passive layer. Avoid high concentrations of bleach to clean stainless steels, as pitting of the surface can occur. Arrange tools by metal type when cleaning so that galvanic corrosion does not occur as a result of contact between dissimilar metals. Additionally, to avoid ferrous contamination of the surface (the transfer of ferrous particles) do not store stainless steel tools with carbon steel tools. 


Movable parts should be lubricated after cleaning or Passivation. Spray instrument oil and let drain (do not wipe) before autoclaving. 


Follow the manufacture’s equipment recommendations. Remove any dirt, grease, or chemicals from the surface before autoclaving to eliminate staining or spotting. Follow recommended drying times and procedures to prevent water spotting mentioned below.


All Humera Sankyo Corporation tools are guaranteed against defects in material or workmanship. If a product fails as a result of a defect, we will replace or repair it at no cost. This warranty is void under conditions where the tool has been used for a purpose not intended, has been altered in any way, or has not been properly maintained. For non-warranty related returns, material will be accepted for credit if returned unused in its original condition and packaging. A restocking fee of 5-10% may be applied and will be determined at the time of return. All returns, regardless of reason, must be accompanied by a Return Material Authorization (RMA) number. 



This is a process which is done to protect the instruments form corrosion and rust, also it is implemented to remove any traces of rust left. 


Director Quality Assurance is responsible for implementation of this test. 


Ø      65% Nitric Acid (2.5 Liters) + Sodium Di Chromate (1 Kg) +

Ø      Potassium Di Chromate (1 Kg)

Ø      Put all these chemicals in 70 Liters of water.

Ø      All the instruments are dipped in the solution for three minutes

Preparation of Hot Water

Ø      Trisodium Phosphate Crystals (50 gms+ Citric Acid Crystals (50 gms)

Ø      Add the Chemicals in 4 liters water.

Ø      Boil the water up to 100 degree centigrade.


Ø      Scrub in hot water suing detergent (Trisodium Phosphate), for thirty minutes.

Ø      Rinse with hot water removes residual chemicals

Ø      Wipe with clean moistened cloth to remove localized contamination.

When specified by customer the following steps are taken to achieve corrosion resistance. In case of stainless steel parts or tow avoid product contamination after Passivation.

Ø      Rinse several times with hot water.

Ø      Dry thoroughly after the final water rinse.


Ø      Make sure that the instruments are completely immersed in the water.

Ø      Be very careful as the water is hot.

Ø      Watch the instruments thoroughly and check weather there is any sign of rust or   corrosion.



This test is carried out to check any signs of corrosion on the instruments and also PH level of the solution is check to identify the acidity or basicity.


Distilled water is prepared by putting sodium bicarbonate in water with a ration by weight PH level checking instruments is also updated.


Ø      Immerse the instruments in a non-reactive container of distilled water.

Ø      Boil the water and maintain temperature for 30 plus minus 1 minute.

Ø      Remove the heat source.

Ø      Let the instruments remain immersed for up to 3 hrs 1 minute plus minus.

Ø      Remove the instruments and put the instruments on towel for 2 hrs 10 minutes plus minus.

Ø      Record PH-level of water before discarding

Ø      If PH-level is outside 6.5 to 7.0 ranges, then instruments were not cleaned thoroughly and should be retested accordingly.


Ø      Adjust the timer at half an hour.

Ø      Don’t discard the water before the PH Level is checked.

Ø      Note down the results of the experiment properly.

Ø      Immersion time is the water and drying up time should be noted properly.



Stainless steel is a low carbon steel which contains chromium at 10% or more by weight. It is this addition of chromium that gives the steel its corrosion resistant properties. The chromium content of the steel allows the formation of an invisible chromium-oxide film on its surface. If oxygen is present, even in small quantities, this film self-repairs if damaged mechanically or chemically. Corrosion resistance of stainless steel is enhanced by increased chromium content and the addition of other elements such as molybdenum, nickel, and nitrogen.

The three main classifications of stainless steel are identified by the alloying elements which form their microstructure. Austenitic steels have austenite (face centered cubic crystal) as their primary phase. These are alloys containing chromium and a major proportion of nickel. Austenitic steels are not thermally hardenable but have excellent corrosion resistance. Ferritic steels have ferrite (body centered cubic crystals) as their main phase. These steels have a low carbon content and contain chromium as the main alloying element. Usually between 13% and 17%. Ferritic steel is less ductile than austenitic steel and is not thermally hardenable. Martensitic steels are low carbon steels typically containing 12% chromium, a moderate level of carbon, and very low levels of nickel. Martenitic steels are distinguished from other stainless steels in their ability to achieve high hardness by a heat treatment that products martensite (a supersaturated solid solution of iron characterized by a needle-like microstructure)

Type 410 is a Martensitic alloy similar to 405 but with a higher carbon content and no aluminum. It is this increase in carbon and absence of aluminum that improve the mechanical properties and strength of 410 by making it hardenable steel to regular carbon and alloy steels.

Type analysis of 410 stainless steel


Carbon 0.15% max.     Manganese   1.00% max                      Phosphorus 0.040 % max

Sulfur   0.030%max      Silicon         1.00%max                       Chromium 11.5/13.50%

Type 420 stainless steel is a Martensitic alloy that is strengthened by the addition of carbon at a 0.15% minimum (0.30% nominal) compared to the 0.15% maximum for type 410. Along with carbon, chromium content is also slightly increased to offset the tendency of the higher carbon content to lower the alloy’s resistance to corrosion. In the hardened and tempered condition, the alloy’s yield strengths are substantially greater than type 410. Type 420 is used for such applications as surgical and dental instruments, cutlery, scissors, valves, and ball bearings.

Type analysis of 420 stainless steel

Carbon 0.15% max.     Manganese 1.00% max                        Phosphorus 0.040 % max

Sulfur   0.030%max      Silicon        1.00%max                        Chromium 12.00/14.00%

Type 440-C is a thermally hardenable, martensitic stainless steel alloy combining corrosion-resistant properties with maximum hardness. Both carbon (0.95% - 1.2%) and chromium (16-18%) contents are increased substantially to impart hardness. While it is the strongest of all stainless steel alloy, its high carbon content reduces its corrosion resistance.

Type analysis of 440-C stainless steel

Carbon 0.95/1.20%.    Manganese 1.00% max              Phosphorus 0.040 % max

Sulfur   0.030%max      Silicon        1.00%max              Chromium 16.00/18.00%

                                     Molybdenum 0.75% max

Rockwell Hardness:

We have accurate furnaces to obtain Rockwell hardness at C-40 to C-45 on Forceps and between C-50 to C-55 on Scissors and Bone Instruments.