Manufacturing Process
Prowa Medical Instruments | Manufacturing Process
Forging
The instruments are made through Drop Forging Hammers using Dyes made of the best quality D-2 Steel. The forgings later are put through the process of overall / ring trimming, and acid cleaning / pickling.
Annealing
Before the forging is sent out for annealing, a visual inspection of forged instruments is made to ensure desired pattern and measurements are met with.
Annealing is a process which makes Stainless Steel soft for machining. Forged surgical instruments are annealed in vaccum furnaces to prevent corrosion. This is a slow process where forged pieces are heated to a predetermined temperature and later allowed to cool down very slowly over a period of time. This allows for easy machining and makes it supple for forming, shaping and sizing in the later stages.
Milling
Annealed products are machined and milled based on the requirements of the final design. Special cutters are used for introducing teeth, serrations, ratchets, box-joints etc., ensuring exact perfection before filling.
Grinding
Milled products are next grinded using high speed grinding wheels and belts, to remove any excess material left in the forging process and also to size the instruments as per the required tolerances.
Heat Treatment
Instruments when sized and set for perfect fit, are then heat treated in highly sophisticated furnaces. This process is used to harden the annealed instruments as per the final requirements. This is also an important step as the hardness of the instruments must be within the acceptable range. Extreme hardening causes the instruments to break and not work properly.
Hardness Test
The instruments are now tested using diamond tipped Rockwell hardness test equipment to ensure proper hardness of instruments.
Filling
Technicians take the adjoining pieces of instruments and set them together. At this stage, the final shape of the instrument emerges and is joined together using screws or rivets in case of forceps and scissors. The serrations, ratchets, and teeth are also aligned and straightened to form the perfect fit.
This process is very important in order to get accurate size, design, weight and pattern of the instruments based on the master sample.
Electro Polishing
Instruments are next grinded to remove deep scratches from the medium-coarse grinding and sizing in the previous stages, as per the requirements.
Electro Polishing is a process of anodically smothering the surface of instruments that gives a shiny look which also removes burs from instruments.
Polishing
In this stage, experienced workers give the finish shape to instrument and make it smoother through use of different polishing equipments.
Sand Blasting
Instruments are then transferred to sand blasting unit where the joint, teeth and ratchet of instruments are sand blasted to give them matt look and protect from rust while in usage. Sand blasting is effective for removing light or dark spots over instruments surface.
Sharp Edge Cleaning
Sharp edges are cleaned / removed to make the instruments smooth from all ways to avoid any failure during use.
Technical Inspection
Instruments are adjusted in terms of teeth, ratchet, box joints, and movement in order to give perfect functionality to instrument while intended use. Instruments that do not pass QC are sent back to an earlier step depending on the corrective action.
Passivation
During handling and processing operations such as forging, machining and forming; particles of Iron, tool, steel or shop dirt may be embedded in or smeared on the surface of stainless steel components.
These components may reduce the effectiveness of natural oxide (passive) film that forms on stainless steel instruments.
Final Polishing / Buffing
After technical inspection, all the instruments are polished in per the final requirements either to a mirror polish, satin or sand finish.
Ultrasonic Cleaning
A finished product is now subjected to deep cleansing and decreasing of oils and finishing materials in ultrasonic cleaning machines before sending it for final inspection.
Final Inspection
Instruments are individually hand-examined. Each and every feature of an instrument is examined including serrations, ratchets, jaws, and teeth while testing the cutting, grasping, and moving functions.
Labeling
Instrument that are approved by the final inspection are finally laser or stencil marked.
Color Coating (Optional)
Once instruments are ready, the are color coated (if required) according to customer’s requirements, placed in a controlled industrial oven for certain amount of time for color to harden.
Packaging
Finally, each instrument is manually cleaned to make sure of removal of any grease, oil and foreign particles that may have been embedded during previous stages.
Final packaging is carried out in a controlled environment where humidity and temperature are well controlled. Specialized gloves, head netting and other personal wears are used to control packaging.
Instruments are then packed in polythene bags, labeled as per the requirements of customer and make them ready for dispatch.
Checking the HRC of instruments
After the completion of vacuum heat treatment process at Prowa Medical Instruments, the next step is to check whether the required steel hardness has been achieved. Proper steel hardness is a very critical factor and will vary depending upon the grade of steel, along with the parameters used during the heat treatment process. Only when the required HRC is acquired, the production lot papers are stamped and the HRC reading is mentioned on the lot tracking card so that it can be used in future for trackback, if necessary.
Digital Rockwell Hardness Tester
This is an automated machine with digital display that reveals an accurate HRC reading in few seconds through the process of diamond indentation.
Manual Rockwell Hardness Tester
This is the workhorse of the industry. It is reliable, accurate, and fast and can cover almost the whole range of our instruments when checking for HRC.
All instruments that go through vacuum heat treatment, must go through the HRC testing method on sample basis before they can be sent for further production processes.
Welding Technologies in the Instrument Manufacturing
Prowa Medical Instruments uses different types of welding technologies throughout its manufacturing facilities. The choice of technology depends upon the material, profile of the workpiece, and technical requirement of the instrument.
Spot Welding
This is a form of electric resistance welding. Two brass electrodes are used to ‘spot weld’ together two sheets of metal that are placed on top of each other. Prowa Medical Instruments uses this type of welding to create multiple ‘welding spots’ on the tail end of its tweezers (tissue forceps).
Argon Welding
Prowa Medical Instruments uses this technology for welding tungsten carbide (TC) rods onto stainless steel scissors. The TC instruments are more durable and premium and require excellent weld strength and finish.
Laser Welding
This is one of the latest forms of welding that uses pure laser source for heating and welding the elements. Prowa Medical Instruments uses laser welding for two different reasons; for repair purposes of instruments, and also for assembly welding two different parts to the same instrument.
Induction Welding
This is one of those mesmerizing technologies that a person can keep watching for extended time. Through this electromagnetic induction process, Prowa Medical Instruments welds together Tungsten Carbide inserts to stainless steel instruments (forceps and needle holders).