Analyse van verschillende oppervlaktebehandelingsprocessen

Analyse van verschillende oppervlaktebehandelingsprocessen

There are so many oppervlaktebehandeling processes! The boring definitions are hard to understand? This blog organizes the definitions and process diagrams for you, making it easy for you to understand the various surface treatment processes in minutes!

1. PVD (Physical Vapor Deposition)

PVD is an industrial manufacturing process, belonging to a type of coating technology, primarily using physical means to heat or excite materials to deposit thin films. This technique, also known as vacuum coating or vapor deposition, is commonly employed in surface treatments of cutting tools, various molds, and in the manufacturing processes of semiconductor devices.

AD: Compared to chemical vapor deposition, physical vapor deposition has a wider range of applications. Almost all materials can be used to prepare thin films through physical vapor deposition.

DIS: The uniformity of film thickness is indeed a concern in physical vapor deposition.

2. Mechanical Polishing

Mechanical polishing relies on the grinding and rolling action of very fine polishing particles, as well as cutting and plastic deformation of the material surface, to remove protrusions from the polished surface of the metal sample, thus obtaining a smooth surface.

AD: The equipment structure is relatively simple, and the price is generally lower compared to other methods.

DIS:

• Mechanical polishing is challenging for polishing workpieces with complex shapes or surfaces featuring special patterns or textures.
• It tends to generate metal dust, which can affect the health of polishing workers.
• It requires a high level of skill from workers, making it difficult to control the consistency and stability of workpiece quality.
• Mechanical processing inevitably leaves microscopic cracks and residual stress on the workpiece surface, which may affect the quality and lifespan of the workpiece and pose safety hazards for production.

  

3. Chemical Polishing

Chemical polishing is a method that relies on the selective dissolution of surface irregularities on samples through the chemical etching action of chemical reagents, eliminating scratches and leveling surfaces.

AD: Chemical polishing does not require special fixtures or DC power supply equipment. It is simple to operate, energy-efficient, and not limited by the size or shape of the workpiece. Additionally, the direct cost of polishing is relatively low.

DIS: The pollution issue is particularly severe, as handling the waste liquid generated during the polishing process can increase costs.

4. Electropolishing

Electropolishing, also known as electrochemical polishing or electrolytic polishing, utilizes the phenomenon of electrochemical dissolution generated by the anode in an electrolytic cell to selectively dissolve micro-protrusions on the anode surface, resulting in a smoother surface. In this process, the workpiece to be polished serves as the anode, while an inert metal acts as the cathode. Both poles are immersed in an electrolyte solution, and a direct current is passed through to achieve selective anodic dissolution, thereby increasing the brightness of the workpiece surface.

AD:

1. Consistent internal and external color, long-lasting luster, and the ability to smooth out concave areas that mechanical polishing cannot reach.
2. High production efficiency and low cost, suitable for large-scale sample preparation.
3. Enhanced corrosion resistance of the workpiece surface, applicable to all stainless steel materials.

DIS:

1. The quality of electrolytic polishing is influenced by the specifications of the electrolyte, as well as the current and voltage settings, making it difficult to determine the correct parameters.
2. Achieving satisfactory results for samples with cast iron or impurities is more challenging.
3. The electrolyte composition is complex, requiring careful attention to safety during use.

   

   

5. Spray Painting

spray painting is a coating method where the liquid is dispersed into uniform and fine droplets using a spray gun or disk atomizer, typically with the aid of pressure or centrifugal force, and applied to the surface of the object to be coated.

AD: Fast construction, good surface smoothness, no texture differences.

DIS: Spray painting machines are relatively expensive, and there is a significant amount of paint wastage.

6. Powder Coating

Powder coating is a process where powder coating material is sprayed onto the surface of a workpiece using powder coating equipment (electrostatic spray gun). Under the influence of static electricity, the powder evenly adheres to the surface of the workpiece, forming a powdery coating layer.

AD:

• Powder coatings do not contain VOCs (volatile organic compounds), eliminating issues such as fire hazards, toxicity, and environmental pollution.
• Minimal material loss and high utilization.
• Easy control of coating thickness, high construction efficiency, low construction difficulty, and energy and labor-saving.
• Scratch-resistant, impact-resistant, durable, and excellent chemical resistance.

DIS:

• The investment required for manufacturing powder coatings and replacing coating equipment is significant.
• Color matching for powder coatings can be challenging, and changing colors or types during coating is more cumbersome and costly.
• Cannot be used on substrates with poor heat resistance such as plastic, wood, or paper.
• Powder coatings are susceptible to clumping during storage due to pressure, temperature, and humidity fluctuations.

  

7. Sandblasting

Bij zandstralen, waarbij perslucht als drijvende kracht wordt gebruikt, worden met hoge snelheid straalstromen van schurende materialen (zoals koperertszand, kwartszand, amaril, ijzerzand en zeezand) op het oppervlak van werkstukken gespoten, waardoor het uiterlijk of de vorm van het werkstukoppervlak verandert. Door de impact en de snijwerking van de schuurmiddelen op het werkstukoppervlak worden de oppervlaktereinheid en -ruwheid van het werkstuk veranderd. Dit proces verbetert de mechanische eigenschappen van het werkstukoppervlak, verbetert de weerstand tegen vermoeiing, verbetert de hechting tussen het werkstuk en de coatings, verlengt de duurzaamheid van de coatings en vergemakkelijkt het nivelleren en decoreren van de coating.

AD:

• Zandstralen kan het oppervlak van objecten snel reinigen en de oppervlaktekwaliteit na het zandstralen is goed, waardoor de levensduur van objecten effectief wordt verlengd.
• Zandstralen kan worden toegepast op verschillende soorten objecten, of ze nu van staal, keramiek of kunststof zijn.
• Eenvoudige bediening.

DIS:

• Zandstralen genereert een grote hoeveelheid stof en afval, wat milieuvervuiling veroorzaakt.
• Zandstralen vereist bepaalde kennis en vaardigheden; onjuiste handelingen kunnen het oppervlak van objecten beschadigen.
• Zandstralen vereist regelmatig onderhoud en reiniging om een goede werking te garanderen.

  

8. Shot Peening

Shotpeening is een veelgebruikt proces voor oppervlakteversterking in fabrieken. Hierbij wordt het oppervlak van werkstukken gebombardeerd met shotdeeltjes om restdrukspanning in te planten en zo de vermoeiingssterkte van het werkstuk te verhogen door koud te bewerken. Deze techniek wordt veel gebruikt om de mechanische sterkte, slijtvastheid, vermoeidheidsweerstand en corrosiebestendigheid van componenten te verbeteren. Soorten shotdeeltjes zijn onder andere staalschot, gietijzerschot, glasparels, keramische parels, enz.

AD:

• Eenvoudige apparatuur, lage kosten
• Niet beperkt door de vorm en positie van het werkstuk
• Handige bediening

DIS:

• Slechte werkomgeving
• Lage uitvoer per eenheid
• Lager rendement vergeleken met gritstralen

  

9. Galvanisch verzinken

Galvaniseren is een proces waarbij door middel van elektrolyse een metaallaag wordt aangebracht op het oppervlak van metalen of andere materiële onderdelen. Dit proces helpt bij het voorkomen van metaaloxidatie (zoals roesten), verbetert de slijtvastheid, geleidbaarheid, reflectiviteit, corrosiebestendigheid en verbetert de esthetiek.

AD: Aantrekkelijk uiterlijk van het oppervlak, uitstekende corrosiebestendigheid, sterke mechanische eigenschappen.

DIS: Onjuiste behandeling van gegenereerd afvalwater en uitlaatgassen kan leiden tot milieuvervuiling, hoog energieverbruik en mogelijke gezondheidsrisico's voor mensen.

10. Anodiseren (anodische oxidatie)

Anodiseren verwijst naar het proces waarbij aluminium en aluminiumlegeringen, onder specifieke elektrolyt- en procesomstandigheden, een oxidelaag vormen op het oppervlak van aluminiumproducten (de anode) door de inwerking van een externe elektrische stroom.

AD:

• Anodiseren kan een dichte oxidelaag vormen op het oppervlak van metaal, waardoor oxidatie en corrosie effectief worden voorkomen.
• Het verhoogt de hardheid van het metaaloppervlak, waardoor het beter bestand is tegen slijtage en krassen en dus langer meegaat.
• Verschillende kleuren oxidelagen die op het metaaloppervlak worden gevormd, verbeteren het esthetische uiterlijk en de decoratieve eigenschappen.
• De ruwheid van het metaaloppervlak neemt toe na het anodiseren, wat de hechting tussen coatings en substraten bevordert en de coating duurzamer maakt.
• Een isolerende oxidelaag op het metaaloppervlak verbetert de isolatie-eigenschappen.

DIS:

• Vooral bij grote oppervlakken of diktes van metalen producten verhoogt een aanzienlijk energieverbruik de productiekosten.
• Strikte controle van de verwerkingsomstandigheden en bedrijfsnormen is vereist, wat leidt tot langere verwerkingstijden die de productie-efficiëntie kunnen beïnvloeden.
• De oxidelaag die gevormd wordt tijdens het anodiseren kan de afmetingen en vormen van het metaal beïnvloeden, wat een zeker risico vormt voor de normale werking van onderdelen met hoge precisie of hoge eisen.
• Het anodiseerproces is voornamelijk geschikt voor bepaalde metalen zoals aluminium, magnesium en titanium. Voor andere metalen zoals staal, koper en zilver is het anodiseerproces mogelijk niet toepasbaar of effectief.
• Hoewel de oxidelaag die gevormd wordt door anodiseren een hoge hardheid en corrosiebestendigheid heeft, kan hij beschadigd raken onder bepaalde omstandigheden zoals mechanische slijtage of chemische corrosie, waardoor regelmatig onderhoud en reparatie nodig zijn.

11. EPD (elektroforetische afzetting)

Elektroforetische afzetting is een proces waarbij, onder invloed van een toegepaste spanning tussen positieve en negatieve polen, geladen verfdeeltjes in een elektroforetische coating naar de kathode migreren. Ze reageren met alkalische stoffen die ontstaan op het kathodeoppervlak en vormen zo onoplosbare afzettingen op het oppervlak van het werkstuk.

AD:

• Veiligheid in productie: Elektroforetische coating gebruikt water als oplosmiddel, waardoor het niet giftig en niet brandbaar is.
• Hoogwaardige coating: Elektroforetische verf heeft een sterke hechting, uniforme dikte en uitstekende corrosiebestendigheid.
• Hoge benuttingsgraad: Elektroforetische verf wordt efficiënt gebruikt.

DIS:

• Beperkte toepasbaarheid op kleine en middelgrote onderdelen vanwege de beperkingen van de apparatuur.
• Beperkt tot geleidende substraten en enkellaags coating: Als een onderdeel eenmaal is gecoat met elektroforetische verf, wordt het een isolator die verdere elektroforetische coating voorkomt.
• Beperkte kleuropties: Elektroforetische verfkleuren zijn overwegend donker.

  

12. Oxidatie met microboog

Microboogoxidatie, ook bekend als microplasma-oxidatie, is een proces waarbij, door een combinatie van elektrolyt en specifieke elektrische parameters, een onmiddellijk hogetemperatuur- en hogedrukeffect wordt gegenereerd op het oppervlak van aluminium, magnesium, titanium en hun legeringen via boogontlading. Dit proces resulteert in de groei van een keramische coatinglaag die voornamelijk bestaat uit metaaloxide op het substraat.

AD:

• De metaaloxidelaag die gevormd wordt door microboogoxidatie wordt metallurgisch versmolten met het substraat, wat resulteert in een hoge hechtsterkte. De keramische laag heeft een dichte structuur, een goede taaiheid en vertoont eigenschappen zoals slijtvastheid, corrosiebestendigheid, schokbestendigheid bij hoge temperaturen en elektrische isolatie. Het kan ook voldoen aan eisen voor thermische isolatie, katalyse, antibacteriële eigenschappen, enz.
• Het proces heeft een breed scala aan toepassingen en is milieuvriendelijk tijdens de verwerking.

DIS: Het oppervlak kan ruw en oneffen zijn.

13. Metal Brushing

Metal brushing is a manufacturing process involving repeatedly scraping aluminum plates with sandpaper to create lines. The main process consists of three parts: degreasing, sanding, and washing. During the brushing process, a special film technique applied after anodizing treatment enables the metal surface to form a film layer containing metal components. This process makes each fine scratch clearly visible, allowing the metal to exhibit a subtle sheen amidst its matte finish.

AD:

• Wear-resistant, high-temperature-resistant, and corrosion-resistant.
• Easy maintenance and cleaning in daily use.
• Fine texture.
• Long lifespan.

DIS: Relatively expensive price.

14. Etching

Etching is a technique that removes part of the material through chemical reactions or physical impacts. Etching typically refers to photolithographic etching, where after exposure and development, the protective film on the area to be etched is removed. When exposed to a chemical solution during etching, it dissolves and corrodes the material, creating a concave or hollow effect.

AD:

• Metal etching processes can create extremely precise shapes and patterns, and the consistency of the metal etching process ensures that each product in mass production has the same quality and characteristics.
• Etching processes can be applied to various metals, including copper, nickel, gold, silver, iron, and some non-metallic materials.
• Metal etching processes generate relatively little waste, and in many cases, waste can be recycled and treated.
• High efficiency.

DIS:

• Etching processes require precise control of factors such as chemical solution concentration, temperature, and etching time, leading to high complexity.
• High equipment and manufacturing costs: Etching processes require specialized equipment and materials such as etching tanks, power supplies, heat exchangers, etc. Additionally, precise control of the production process is needed to ensure product quality and consistency.
• Workers may be exposed to hazards such as chemical substances, high temperatures, and noise.

  

15. IMD (In-Mold Decoration technology)

IMD, also known as non-painting technology, is an internationally popular surface decoration technique. It involves applying a surface-hardened transparent film, printing the pattern layer in the middle, and injecting the back molding layer. The ink is sandwiched between layers, making the product resistant to friction, preventing surface scratches, and maintaining color brightness for an extended period without fading.

AD:

• Strong scratch resistance and corrosion resistance.
• Long service life.
• Excellent three-dimensional effect.
• Strong resistance to dust, moisture, and deformation.
• Color can be changed as desired.
• Patterns can be easily modified.

DIS:

• Long lead time.
• Prone to issues such as film detachment and distortion.
• High defect rate in products.

  

  

16. OMD (Out Mold Decoration)

OMD is an extension of IMD (In-Mold Decoration) technology that integrates visual, tactile, and functional elements. It combines printing, texture structure, and metallization characteristics to achieve 3D surface decoration.

AD:

• Substrate material is not limited, can be metal or plastic.
• Can achieve 3D shapes.
• Can encapsulate internal structures (back-molding).
• Allows for simultaneous processing of multiple small products.

DIS:

• High equipment investment.
• Unable to achieve complex 3D shapes.

  

17. Laser Engraving

Laser engraving, also known as laser etching or laser marking, is a surface treatment process based on optical principles. It involves using a laser beam to engrave permanent marks on the surface of a material or within transparent materials.

AD:

• Fast marking speed, low cost
• Attractive patterns, high resolution, and high precision
• Wear-resistant

DIS: Limited color options

18. EDM (Electrical Discharge Machining)

EDM is a specialized machining method that utilizes the erosive effect produced by pulsed discharges between two electrodes immersed in a working fluid to remove conductive materials. It is also known as spark machining or spark erosion machining. The tool electrode is typically made of materials with good conductivity, high melting points, and easy machinability, such as copper, graphite, copper-tungsten alloy, and molybdenum. During the machining process, there is wear on the tool electrode, but it is usually less than the material removal from the workpiece metal, and in some cases, it can be negligible.

AD:

• Capable of machining materials and complex-shaped workpieces that are difficult to cut using conventional cutting methods, such as sharp corners.
• Does not produce burrs and tool marks.
• Tool electrode material does not need to be harder than the workpiece material.
• Enables automation due to the direct use of electrical energy.

DIS: Low efficiency.

19. Laser Etching

Laser etching involves the treatment of steel surfaces with high-energy density lasers to create patterns such as snake skin, etchings, pearlescent finishes, or other forms of textures.

AD: High welding accuracy and small heat-affected zone, suitable for repairing precision molds.

DIS:

• Welding wire is relatively expensive, leading to lower efficiency.
• Bulky equipment makes mobility difficult, and unsuitable for on-site operations. Welding repairs need to be performed on a workbench, making it impractical for large molds or workpieces.
• Repairing irregular-shaped defects can be challenging compared to straight-line repairs.
• Large heat-affected zones during welding repairs increase the likelihood of workpiece sagging, deformation, and undercutting.
• Lower welding accuracy, unable to meet the requirements of high-precision molds.
• Many mold repairs require preheating, insulation, and other processes, making them cumbersome and time-consuming.

  

20. Pad Printing

Pad printing, also known as tampon printing, is a specialized printing method that involves using a steel (or copper, thermoplastic) plate with an engraved design. A curved surface pad made of silicone rubber material is used to pick up ink from the plate's surface. The ink is then transferred onto the desired object's surface by pressing the pad against it, resulting in the printing of text, patterns, or other images.

AD:

• Wide application range: Pad printing is commonly used on products with recesses or on the back of objects where screen printing is not feasible. It can achieve clean printing results even on uneven surfaces.
• Convenient operation: Equipment can be operated semi-automatically or fully automatically, with low labor costs and high production efficiency.

DIS:

• Ordinary results.
• Pad printing cannot create patterns with large areas.
• Due to the clear edges of the recesses processed by steel plates, gradient colors cannot be produced.

  

21. Screen Printing

Screen printing refers to a printing method that uses a screen as the printing plate, which is made into a screen printing plate with images or text through photosensitive plate-making methods. Screen printing consists of five main elements: the screen printing plate, squeegee, ink, printing table, and substrate. The basic principle of screen printing is that the ink can pass through the mesh holes of the image/text part of the screen printing plate, while the non-image/text part of the mesh holes cannot pass through the ink. During printing, ink is poured into one end of the screen printing plate, and a certain pressure is applied to the inked area on the screen printing plate using a squeegee. At the same time, the squeegee moves steadily towards the other end of the screen printing plate, and the ink is squeezed from the mesh holes of the image/text part onto the substrate.

AD:

• Screen printing can use various types of inks: oil-based, water-based, synthetic resin emulsion-based, powder, etc.
• Screen printing plates are flexible and have a certain elasticity, suitable for printing on soft materials such as paper and fabric, as well as on hard objects such as glass and ceramics.
• Screen printing requires low printing pressure, making it suitable for printing on fragile objects.
• Thick ink layer with strong coverage.
• Not limited by the surface shape or size of the substrate. Screen printing can be applied on flat surfaces, as well as on curved or spherical surfaces. It is suitable for printing on both small and large objects.

DIS:

• Only one color can be printed at a time.
• Plate-making and film output costs are relatively high, making it unsuitable for small-batch production.
• Poor performance when used on uneven surfaces.
• Ink quantity cannot be easily controlled.

  

22. Direct Thermal Printing

Direct thermal printing refers to a method where a thermal-sensitive agent is coated on paper to create thermal recording paper. When subjected to heat, the thermal recording paper causes a physical or chemical change in the substance (coloring agent) to produce an image.

AD:

• Fast printing speed and low noise level.
• Clear printing and easy to use.

DIS: Direct thermal printers cannot print duplicates directly, and the printed documents cannot be permanently archived.

23. Thermal Transfer Printing

Thermal transfer printing works by first digitally printing the desired image onto transfer paper using specialized transfer ink in an inkjet printer. Then, a dedicated heat transfer machine applies high temperature and pressure to accurately transfer the image onto the surface of the product, completing the printing process.

AD:

• Simple printing process with accurate positioning.
• Does not cause damage to the material.
• Suitable for printing images with color gradients and on multiple materials.

DIS:

• Poor breathability.
• Fine cracks may appear in the printed pattern on clothing when stretched.
• Poor durability.

  

24. Planographic Printing

Planographic printing is a printing method that uses flat printing plates. It is the most widely used printing process globally and is also employed in the manufacturing of semiconductor and MEMS devices. Planographic printing, also referred to as "offset printing" or "indirect printing," is a common commercial printing technology. It involves transferring images or text from flat printing plates onto rubber blankets, which are then used to print onto paper or other materials.

AD:

• Fast printing speed, relatively low printing cost, and high print quality.
• Suitable for large-scale and repeat printing jobs.

DIS:

• Requires preparation of preliminary work such as plate making and setup.
• Not suitable for short-run printing and customization.

  

  

25. Curved Surface Printing

Curved surface printing involves placing ink into engraved plates with text or patterns, and then transferring them onto curved surfaces. The text or patterns are then transferred onto the surface of the molded product using the curved surface. Finally, methods such as heat treatment or ultraviolet light exposure are used to cure the ink.

AD:

• Wide applicability: It can be used for printing on various curved surfaces, such as cylinders, spheres, and irregular shapes.
• High customization: It can print complex patterns, text, and images on curved surfaces, achieving personalized customization.
• High production efficiency, and stable quality.

DIS:

• Higher cost due to the need for more equipment and technical support.
• Subject to limitations of printing machinery and technology, some specific shapes of curved surfaces may not be fully covered.
• Design complexity may increase as designers need to consider the variations and distortions of curved surfaces.
• Ink curing in surface printing may be uneven or incomplete due to the influence of the surface shape.

  

26. Hot Stamping

Hot stamping refers to a process where hot stamping materials or hot stamping patterns are transferred onto objects such as paper, cardboard, fabric, or coated materials using heat and pressure. Hot stamping is commonly used in the binding process, especially on covers.

AD:

• Precision and meticulous craftsmanship, with minimal equipment errors, resulting in finer patterns on hot-stamped items.
• Capable of performing three-dimensional hot stamping.
• Energy-efficient, reducing environmental pollution, and offering fast hot stamping speeds.

DIS:

• The high precision requirement of the hot stamping process for equipment leads to increased costs.
• The process involves relatively complex and intricate procedures.

  

27. Water Transfer Printing

Water transfer printing is a technique that transfers printed images or graphics from a flat surface onto the surface of different materials using water. It is divided into two types: water immersion transfer and water overlay transfer (curved surface overlay). Water immersion transfer is mainly used for transferring text and photographic images, while water overlay transfer is primarily used for complete transfer over the entire surface of an object.

AD:

• Aesthetic appeal: It can transfer any natural patterns, photos, and graphics onto products.
• Innovation: Water transfer printing technology can overcome the limitations of traditional printing methods such as heat transfer, offset printing, screen printing, and surface coating, allowing for the creation of complex shapes and angles.
• Versatility: Applicable to surface printing on hardware, plastics, leather, glass, ceramics, wood, etc. (not suitable for fabric and paper).
• Personalized design.
• Efficiency: No need for plate-making; direct printing and immediate transfer.

DIS:

• Transferred images or graphics are prone to deformation.
• Fully manual operation leads to high labor costs and low production efficiency.

  

28. Flat Screen Printing

Flat screen printing involves fixing printing molds onto square frames, which are usually made of polyester or nylon mesh (screen) with hollow patterns. The patterned areas of the screen allow ink to pass through, while the non-patterned areas are sealed with a polymer film layer to block the mesh openings. During printing, the screen is pressed tightly against the fabric, ink is poured onto the screen, and a squeegee is used to repeatedly scrape and press the ink through the patterns onto the fabric surface.

AD:

• Convenient plate-making process, with large repeat lengths, multiple color matching options, ability to print fine patterns without color bleeding, high ink volume, and the capability to achieve a three-dimensional effect. Suitable for printing on silk, cotton, synthetic fabrics, and knitted fabrics, especially for high-end fabrics with small batches and multiple variety requirements.
• Hand scraping of the ink on the hot table allows for unlimited printing repeats.

DIS:

• Due to the long distance between color frames, it is difficult to achieve overlapping colors.
• Manual fabric placement, manual lifting of the frame, and hand scraping of the ink result in high labor intensity and uneven ink scraping.
• The heat source for the hot table is typically steam heating, though some use electric heating, which consumes a lot of electricity and is prone to accidents.

  

29. Calendering

Calendering, also known as pressing, is the final process of finishing leather. It involves using the plasticity of fibers under heated conditions to flatten or create parallel fine diagonal lines on the surface of the fabric, enhancing the gloss of the fabric. This process is typically carried out using a swing calender machine or a bottom leather rolling machine. Usually, it involves two passes: the first pass compresses the leather body, done after even wetting, followed by stacking to balance moisture content. The second pass is for calendering, which results in a smooth and glossy leather surface with a compacted leather body, thus achieving the finished leather.

Conclusie

With such an array of surface finishing processes available, navigating through their definitions and intricacies can be daunting. However, this blog streamlines the information by organizing definitions and process diagrams, making it effortless to grasp the various surface treatment techniques in just a few minutes. Each method's advantages and disadvantages are neatly presented, enabling a quick understanding of their applications, efficiencies, and limitations.

 

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