Choosing mass finishing media and compoundsBy Mike Pelham
International Chemical Co.
International Chemical Co.
Have you ever walked the beach and picked up a small piece of glass with round, smooth edges? This piece of glass is the result of a natural process of deburring with Mother Nature’s ocean waves as the motor, sand as the media and glass as the part.
Mass finishing performs the same kind of deburring and finishing on manufactured components. Often overlooked, it can be one of the final processes in manufacturing. Careful consideration should be given to this important process to ensure you achieve the proper finish for your parts; otherwise manufacturing costs can escalate sharply and parts may not achieve the required finish.
Because mass finishing is often the final step before parts are packaged and shipped to your customer, attention to detail is important. Of special significance is the choice of media and compound used. This article will look at each, with an emphasis on recent advances in technology that can drastically improve mass finishing productivity by promoting a synergistic relationship between media and compound.
Media Selection
The choice of media is a critical factor in both rotary and vibratory finishing processes. Most media fall into one of two categories: Formed media, and crushed media of irregular size and shape.
The choice of media is a critical factor in both rotary and vibratory finishing processes. Most media fall into one of two categories: Formed media, and crushed media of irregular size and shape.
Formed media, usually geometric in shape, include spheres of steel, plastic or glass; ceramics; steel pins; and triangular or cylindrical shapes formed from aluminum oxide or silicon carbide plus bonding agents. Crushed and graded media include granite, aluminum oxide, limestone and quartz. In some cases, small pieces of scrap steel from a forming or stamping operation can be used as well.
The function of media in any mass finishing operation is to increase the volume and weight of the mass in order to promote rapid, precise deburring of part edges and smoothing of surface irregularities. It also provides a cushioning, free-flowing action throughout the load that prevents tangling, peening and nicking of the parts.
Proper selection of mass finishing media and compound depends on the size, configuration and material of the workpiece—in this case, a stainless steel propeller for an outboard engine.
Proper selection of mass finishing media and compound depends on the size, configuration and material of the workpiece—in this case, a stainless steel propeller for an outboard engine.
Media Selection
The choice of media is a critical factor in both rotary and vibratory finishing processes. Most media fall into one of two categories: Formed media, and crushed media of irregular size and shape.
The choice of media is a critical factor in both rotary and vibratory finishing processes. Most media fall into one of two categories: Formed media, and crushed media of irregular size and shape.
Formed media, usually geometric in shape, include spheres of steel, plastic or glass; ceramics; steel pins; and triangular or cylindrical shapes formed from aluminum oxide or silicon carbide plus bonding agents. Crushed and graded media include granite, aluminum oxide, limestone and quartz. In some cases, small pieces of scrap steel from a forming or stamping operation can be used as well.
The function of media in any mass finishing operation is to increase the volume and weight of the mass in order to promote rapid, precise deburring of part edges and smoothing of surface irregularities. It also provides a cushioning, free-flowing action throughout the load that prevents tangling, peening and nicking of the parts.
Two of the main factors in media selection are the size and shape of the parts to be finished. The media must be able to reach all required surfaces without becoming wedged in part features such as holes and recesses. Geometric shapes are widely used where wedging is a potential problem.
Frequently, two sizes of media—one relatively large and one small—are used simultaneously. The large media covers more surface area while the smaller media cushions the action of the large media while getting into restricted part areas, such as between grooves or gear teeth which cannot be reached by the large media. When using media of mixed sizes, a ratio of one part large media to three parts small media usually produces satisfactory results.
Coarse or angular media are useful for removing large burrs and for rounding corners. Media with a rounded shape are recommended when fine finishes are required.
Media-to-parts ratio in a load will generally range from 2:1 to 5:1. Higher ratios should be used when:
- Large or fragile parts are being processed
- Parts may tangle, bend, crimp or nest together
- Soft metals are being finished
- A fine finish is desired
- Hidden or recessed burrs are a problem.
Another option is processing parts with no media—an approach commonly referred to as part-on-part finishing. Many small parts can be finished without media if they are regular in shape, which allows for even contact of all surfaces. The size and shape of the parts, as well as the locations of burrs, are important considerations as well.
When applicable, part-on-part finishing (self-tumbling) is highly economical, because more parts can be loaded into the unit and the time needed to load and maintain media is not a factor. This approach typically requires a longer cycle time and provides little cushioning, so it is not recommended for soft alloys. Part-on-part finishing should not be employed if nesting, tangling, or sticking together of parts is a problem.
Compound Basics
The compounds used in mass finishing are typically mixtures of chemicals blended together to perform certain specific functions.
The compounds used in mass finishing are typically mixtures of chemicals blended together to perform certain specific functions.
Recent advances in additive technology have enabled compound suppliers to formulate more “green” products. The term “green” can be overused from a marketing standpoint, as it appears to be a focal point for pretty much every industry. However, reducing the environmental impact of industrial processes is vital to the survival and future success of finishers and manufacturers alike.
All that being said, mass finishing compounds typically consist of some combination of the following:
- Water, which is an excellent dispersant for concentrated additives.
- Detergents, most commonly referred to as surfactants, which are designed to reduce surface tension and aid in the cleaning process.
- Builders, or additives that act as catalysts to improve the function of other additives. Examples include phosphate or silicate compounds.
- Sequestrant, which are chemicals designed to reduce water hardness or to bind or chelate certain metals into a soluble state.
- Wetting agents, which can act as surfactants, detergents and defoamers.
The broadest way to categorize mass finishing compounds is by their physical form—either liquid or powder. Historically, powders were more common. However, recent advances in surfactant technology have allowed liquid products to replace many powders.
 |
Another classification to think about for compounds is workpiece material—either ferrous or nonferrous. Often times, additives that prevent steels, cast irons and other ferrous materials from rusting can stain or darken aluminum parts.
But the most important classification of mass finishing compounds is by their intended function. These include cleaning, burnishing, deburring, descaling and corrosion inhibition.
Cleaning compounds are often the first products used, and they can remove organic soils such as oils, lubricants and greases. This is important, because these soils must be removed before any additional part processing can take place. It is therefore critical that users select the proper cleaner for their application, taking into consideration the workpiece material, duration of rust protection (if required), additional processing after parts are cleaned and the type and severity of the soils being removed.
Burnishing compounds make metals look cleaner, lighter or darker in color, more attractive, and more reflective or brighter in appearance. Burnishing compounds are vital to the success of the finishing operation because they must clean all metal surfaces, provide rust protection to both the parts and the media and provide the proper amount of foam and lubricity. That’s a tall order, but it is completely attainable with sound formulation practices.
A deburring compound provides chemical lubrication and cushioning so that the deburring process can take place. Its primary functions are to keep the media from glazing or loading up, clean and debur the parts and provide rust protection to the parts and media if necessary.
Descaling compounds remove accumulated scale from parts. The scale may be from rust, heat treat operations or other manufacturing processes. Typically, these types of compounds are highly alkaline or highly acidic in nature. Generally ferrous metals require the use of alkaline products and nonferrous materials require acidic chemicals.
Compound Formulation
Controlling foam is especially important in formulation and selection of mass finishing compounds. In certain applications, foam can be provide a beneficial cushioning effect. However, vibratory bowls require a lower-foaming product.
Controlling foam is especially important in formulation and selection of mass finishing compounds. In certain applications, foam can be provide a beneficial cushioning effect. However, vibratory bowls require a lower-foaming product.
The goal of compound formulators is to prevent users from adding a defoamer to the process. Defoamers can be costly additions that may only mask a deficiency in the mass finishing compound being used. Proper formulation thus requires a balance of additives between those that produce foam and those that suppress foam.
Another important factor is lubricity control. Mass finishing compounds must have lubricity to allow parts and media to “collide” without damaging the parts. Soap can often be referred to as a lubricant; it provides not only lubricity but also detergency
A critical function of any compound formulation is to protect processed parts from rust and oxidation. Traditional methods may have required the application of a solvent-based rust inhibitor, but recent advances have enabled use of water-soluble additives to provide extended rust protection. Our company has formulated compounds used on products that are shipped coast-to-coast with only the water-soluble mass finishing compound as the inhibitor.
Along the same lines, materials that remove rust and oxidation are often found in compounds used for rework or remanufacturing operations where heavy scale, rust and oxidation are being removed. Depending on the metal, these chemicals are usually acidic or caustic.
歡迎來到利豐行的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供精密表面處理的代理商，應對廠商高品質的表面處理需求，我們可以協助廠商滿足您對產業的不同要求，我們有能力達到非常卓越的表面處理品質，這是現有相關技術無法比擬的，表面處理技術皆集中於去毛邊, 去毛刺, 導角, 精密研磨,拋光, VTD PVD工具鍍膜, 光學鍍膜 optical coating, 金屬濺鍍
metallization, absolute chemie 精密CVD/PVD退鍍工藝和 EMAG Precision
Electrochemical Machining 精密電化學加工技術 (ECM / PECM) 取代放電加工), EMAG 硬車削/乾式車削 hard turning, Koepfer 滾齒(齒輪加工製造) 技術, Reinecker, KARSTENS 內外圓研磨外圓+內圓曲面磨削,
Naxos-Union曲柄軸研磨,
凸輪軸, KOPP非圓研磨, SW中心加工機,
EMAG 雷射焊接, 自動化設備.。我們成功的滿足了各行各業的要求，包括：精密需求高的軸承盒、射出成型的模具、高壓空氣閥、航太零配件、超高硬度的切削刀具、醫療配件及汽車用精密五金等等。我們的產品涵蓋了從桌上型到工業級的生產設備；從微細零配件到大型五金配件；從小型生產到大型量產；從半自動到全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗.
OTEC公司專門研發製造金屬和非金屬的精密表面處理技術及設備，如：切削刀具的鎢鋼和高速鋼之表面處理，並廣泛為世界級大廠所採用如：Guhring
oHG；Iskar等等。利豐行引進最先進的去毛邊, 去毛刺, 導角, 精密研磨和拋光技術，並希望提供台灣廠商提昇產業競爭力及生產效益和使用壽命。OTEC精密表面處理技術被認定為世界的領導者之一。去毛邊, 去毛刺, 研磨拋光、邊緣導角、功能性、裝飾性，這些精密表面處理技術除了令人讚嘆外，OTEC的技術整合還考量到生產者的需求，讓生產者在質量上和效益上及成本上有一個完美的平衡。機械操作除了更人性化還能額外整合生產者目前的製造設備。OTEC的產品兼具美觀及實耐用，不佔空間卻能在最小的單位中創造出最大的質量，當你採購了OTEC的設備後，除了擁有出眾的表面處理技術讓您的競爭力提升外，當客戶拜訪您公司時也不免對您令眼相看而發出讚嘆，OTEC是您生意的好伙伴。
另外有 EMAG ECM GmbH (ECM / PECM / uECM) 精微電化學加工技術在未來各種細微加工應用中佔有極大的優勢。該技術之優點係在於其加工能力與材料硬度無關，且能加工出微細及形狀複雜之表面結構，經由該製程加工後之產品表面具有粗糙度佳、無殘留應力及無裂縫產生, 無毛邊刺等優良特性，常應用於航太、光電半導體、醫療器材、綠色能源、模具等產業上，本次研討會中特別邀請國內外知名學者及專家，介紹於精微電化學領域內之各種加工技術，可應用於燃料電池雙極板、生物晶片、微流體動壓軸承、微噴嘴、次世次流體分配閥元件、模具等產品加工上，機會難得，精彩可期。 EMAG
ECM GmbH為精密電化學切削的工程公司，其領先的技術，已在精密電化學切削領域達到量產化的水準。供顧客PECM精密電化學切削生產技術和客制化的製程設備。 Electrochemical machining
/ pulse electrochemical machining / precise electrochemical machining. Electro
chemical machining (ECM) is a method of removing metal by an electrochemical
process.
利豐行事業有限公司 www.li-fung.biz
407台灣省台中市工業區36路2號
電話：+886 (04) 2355-2327
傳真：+886 (04) 2355-2457
E-mail：info@li-fung.biz
407台灣省台中市工業區36路2號
電話：+886 (04) 2355-2327
傳真：+886 (04) 2355-2457
E-mail：info@li-fung.biz
LI FUNG BUSINESS CO., LTD. www.li-fung.biz
407 No.2. 36th Rd., industry Park, Taichung City, Taiwan, R.O.C
TEL：+886-4-2355-2327
FAX：+886-4-2355-2457
E-mail：info@li-fung.biz
407 No.2. 36th Rd., industry Park, Taichung City, Taiwan, R.O.C
TEL：+886-4-2355-2327
FAX：+886-4-2355-2457
E-mail：info@li-fung.biz
精密表面處理館http://lifung.pixnet.net/blog
利豐非傳統加工科技館 http://blog.sina.com.tw/lifung
本館專門提供 OTEC 表面處理技術皆集中於去毛邊, 去毛刺,
導角, 精密研磨,拋光, deburring, smoothing and
polishing. 還有VTD PVD 超硬工具鍍膜 tool coating, 精密光學鍍膜 optical coating, 真空金屬鍍膜 metalization 和 absolute chemie PVD/CVD 退鍍工藝和 EMAG ECM / Precise Electrochemical Machining 精密電化學加工技術, 去毛邊刺, EMAG 硬車削/乾式切削 hard turning, Koepfer 滾齒加工製造技術, Reinecker, KARSTENS外圓研磨+內圓曲面磨削, Naxos-Union曲柄軸研磨, 凸輪軸, KOPP非圓研磨, SW中心加工機, EMAG 雷射焊接, 自動化設備. 其它非相關資料純粹供同好分享.
沒有留言:
張貼留言