CONTRACT FINISHING and FREE SAMPLE PART PROCESSING for Centrifugal Isotropic Finishing and Polishing

If you have parts that need edge or surface finishing and would like to have FREE sample part processing and a quotation developed for finishing the parts please contact Dave Davidson at dryfinish@gmail.com    I can also be reached at 509.230.6821

Model HZ-60 Centrifugal Barrel Machine typically used for high energy processing for deburring, edge-contour, finishing and polishing metal and plastic parts from the aerospace, automotive, medical, dental, electronic, jewelry and other industries.

Some typical parts finished are shown in the application slide gallery shown below. [click on the image to enlarge it].

 

Super-finishing High Performance Automotive Components [Connecting Rods]

Centrifugal Super-Finishing of High Performance Automotive Components

 

Simiular processing on pistons…

Step 1 is a smoothing operation, Step 2 utilizes dry process finishing media to develop the final polished superfinish…

 

For more information contact Dave Davidson:  http://en.gravatar.com/dryfinish 

 

 

Understanding Surface Finishing’s Role in Part Performance Improvement

Mass finishing processes have been widely adopted throughout industry as the optimum methodology for producing advanced edge and surface finish effects on many types of machined and fabricated components. America industry has long been in the forefront in aggressively deploying these methods to improve edge and surface finishing operations.

All too often, situations still exist where archaic, even primitive hand or manual finishing methods are used to produce edge and surface finishing effects.  This is not to say that some industrial part applications are not going to require a manual deburring approach – some do.  In many cases, however, hand or manual methods are still being utilized because more automated or mechanized methods have not been considered or adequately investigated.

An often observed dichotomy in precision manufacturing operations, is a situation that is still all too common.  This is that many manufacturers, after spending vast sums on CNC machining equipment to produce parts to very precise tolerances and specifications consistently, in the end, hand off these expensive parts to a deburring and finishing department that utilizes hand methods, with all the inconsistency, non-uniformity, rework and worker injury potential that implies.  Even when manual methods cannot be completely eliminated, mass media finish techniques can and should be used to produce an edge and surface finish uniformity that simply cannot be duplicated with manual or single-point-of-contact methods.  Developing an overall edge and surface finish continuity and equilibrium can have a significant effect on performance and service life of critical components.

High intensity mass finishing methods can eliminate positively skewed machined surfaces and replace them with plateaued negatively skewed surface profiles

In recent years, mass media finishing processes have gained widespread acceptance in many industries primarily as a technology for reducing the costs of producing edge and surface finishes. The economics are especially striking when manual deburring and finishing procedures are minimized or eliminated.

The first casualty of over reliance on a manual deburring and finishing approaches is the investment the manufacturer has made, often in the millions, for precise and computer controlled manufacturing equipment. The idea behind this investment was to have the ability to produce parts that are uniformly and carefully manufactured to exacting specifications and tolerances.  At this point, in too many cases, the parts are then handed off to manual deburring and finishing procedures that will guarantee that no two parts will ever be alike.

Moreover, the increased complexity and precision requirements of mechanical products have reinforced the need for accurately producing and controlling the surface finish of manufactured parts. Variations in the surface texture can influence a variety of performance characteristics. The surface finish can affect the ability of the part to resist wear and fatigue; to assist or destroy effective lubrication; to increase or decrease friction and/or abrasion with cooperating parts; and to resist corrosion. As these characteristics become critical under certain operating conditions, the surface finish can dictate the performance, integrity and service life of the component

 

The role of mass finishing processes (barrel, vibratory and centrifugal finishing) as a method for removal of burrs, developing edge contour and smoothing and polishing parts has been well established and documented for many years. Less well known and less clearly understood is the role specialized variants of these types of processes can play in extending the service life and performance of critical support components or tools in demanding manufacturing or operational applications.

To understand how edge and surface topography improvement can impact part performance, some understanding of how part surfaces developed from common machining, grinding and other methods can negatively influence part function over time.  A number of factors are involved:

(1) Positive vs. Negative Surface Skewness.  The skew of surface profile symmetry can be an important surface attribute.  Surfaces are typically characterized as being either negatively or positively skewed. This surface characteristic is referred to as Rsk  (Rsk – skewness – the measure of surface symmetry about the mean line of a profilometer graph).  Unfinished parts usually display a heavy concentration of surface peaks above this mean line, (a positive skew).  It is axiomatic that almost all surfaces produced by common machining and fabrication methods are positively skewed.  These positively skewed surfaces have an undesirable effect on the bearing ratio of surfaces, negatively impacting the performance of parts involved in applications where there is substantial surface-to-surface contact.  Specialized high energy finishing procedures can truncate these surface profile peaks and achieve negatively skewed surfaces that are plateaued, presenting a much higher surface bearing contact area.  Anecdotal evidence confirms that surface finishing procedures tailored to develop specific surface conditions with this in mind can have a dramatic impact on part life.  In one example the life of tooling used in aluminum can stamping operations was extended 1000% or more by improved surface textures produced by mechanical surface treatment.

This photo shows bearing surface as seen by 2D and 3D scanning measurement. The surface peaks and asperities are typical of machined or ground surfaces. Photo by Jack Clark, Surface Analytics 

 

After high energy centrifugal finishing the surfaces are far more functional for the bearing application. More isotropic, more plateaued, more negatively skewed and have imparted a beneficial compressive stress. All of these attributes improving the load bearing and tribological properties of the part. Photo courtesy of Jack Clark, Surface Analytics.

(2) Directionalized vs. Random (Isotropic) Surface Texture Patterns.  Somewhat related to surface texture skewness in importance is the directional nature of surface textures developed by typical machining and grinding methods. These machined surfaces are characterized by tool marks or grinding patterns that are aligned and directional in nature.  It has been established that tool or part life and performance can be substantially enhanced if these types of surface textures can be altered into one that is more random in nature. Post-machining processes that utilize free or loose abrasive materials in a high energy context can alter the machined surface texture substantially, not only reducing surface peaks, but generating a surface in which the positioning of the peaks has been altered appreciably.  These “isotropic” surface effects have been demonstrated to improve part wear and fracture resistance, bearing ratio and improve fatigue resistance.

Magnified view of bearing surface after surface peaks have been removed (top series of diagrams). This high intensity  CBF method is an economical way of blending in machining or grinding lines to develop isotrropic surfaces. Optical Interferometry by Jack Clark at Surface Analytics

(3) Residual Tensile Stress vs. Residual Compressive Stress.  Many machining and grinding processes tend to develop residual tensile stresses in the surface area of parts.  These residual tensile stresses make parts susceptible to premature fracture and failure when repeatedly stressed.   High-energy mass finishing processes can be implemented to modify this surface stress condition, and replace it with uniform residual compressive stresses.  Many manufacturers have discovered that as mass finishing processes have been adopted, put into service, and the parts involved have developed a working track record, an unanticipated development has taken place.  Their parts are better—and not just in the sense that they no longer have burrs, sharp edges or that they have smoother surfaces.  Depending on the application: they last longer in service, are less prone to metal fatigue failure, exhibit better tribological properties (translation: less friction and better wear resistance) and from a quality assurance perspective are much more predictably consistent and uniform.

Centrifugal barrel machines such as these can produce exceptional edge and surface finishes in very short cycle times. Accelerated process effects can be developed because of the high speed interaction between abrasive media and part surfaces, and because media interaction with parts are characterized by high pressure by virtue of the high centrifugal forces developed in the processes. Smaller turbine blades can be processed in the 5 x 8 inch compartments in the 12-liter capacity machine shown to the right. Larger centrifugal machines such as the 220 liter or 330 liter capacity machine shown to the left can handle much larger parts as the barrel compartments are as much as 42 inches in length. Larger parts processed in this type of machinery can be processed one at a time within the barrel compartment suspended within the media mass or be fixtured. Barrel compartments can be divided into processing segments to accommodate more than one part.

SUMMARY:
Mass media finishing techniques (barrel, vibratory, centrifugal and spindle finish) can be used to improve part performance and service life, and these processes can be tailored or modified to amplify this effect.  Although the ability of these processes to drive down deburring and surface finishing costs when compared to manual procedures is well known and documented, their ability to dramatically effect part performance and service life are not.

SME Manufacturing’s Knowledge and Resource Specialist

[NOTE: to become a member of SME please use this convenient fax form:  http://www.slideshare.net/dryfinish/sme-senior-memberapp ]

The SME e-Librarian has a new name — “Knowledge & Resource Specialist.”  This change will help provide members a better description of this SME member benefit. Our specialist is asked daily a variety of questions from our members that requires problem-solving and research. You can ask your questions here on SME Connect or in the Knowledge and Resource Center privately, and our specialist will respond.

You may wonder, what types of questions are asked of our specialist?

• Market research on metal plating and treating in the U.S.
• I want to learn more about the coining process.
• What are the commercially available grades of Q&P steel?
• I need information on X-type bearings.
• How a drip irrigation tube with an internal welded nozzle made.
• Looking for research on removing chlorinated parafins found in Hangsterfers Hardcut 5618 from titanium parts using room temperature solvent baths.
• Literature search on adaptive control machining.
• List of German manufacturers with manufacturing locations in the U.S., including German parent company, name of U.S. business, revenue and the number of employees.
• How spring snakes in a can are manufactured.
• Information on passivating stainless steel.
• Cutting plastic with a .010 extended-reach end mill.

You may also wonder the breadth of information that the Knowledge & Resource Specialist can provide?

• Technical Information — a plethora of manufacturing processes and related subjects
• Management and business types of information. (i.e., cost estimating, information about engineering and technical job descriptions, information about companies and/or competitors)
• Market research(current information on specific industries)
• Vendor and supplier lists
• Materials information
• Literature searches
• Articles from magazines and journals
• Difficult to find articles
• Identify Industry standards

The SME Specialist has access to hundreds of resources used to help answer our SME member questions including government databases (NTIS, U.S. Patent & Trademark Office, U.S. Bureau of Labor Statistics, U.S. Census Bureau and others), industry standards databases, Google Science and many other online resources are used.

Ask your questions here today or visit the Knowledge and Resource Center!

——————————
Thomas Bridge PhD,LSME,CMfgE
Chairmen Emeritis
Western Illinois University
Hampton IL
——————————

Dry super-finishing processes and cutting tool edge improvement

• For many decades there has been an awareness of cutting tool edge condition and tool surface finish and the effect it has on piece part quality and tool life. There have been many independent studies, tests, and implementations of edge conditioning methods to create extended life in turning, drilling, and milling cutter tooling – some published but most kept “secret” as a manufacturing advantage.  — Jack Clark, Surface Analytics LLC and Colorado State University
  
  The “Deburr/Finish Tech Group” of the SME has tasked itself to manage the project and use it’s member resource pool to provide tooling, applications, and the necessary documentation and reporting to objectively test cutting tool edge radius improvement on tool life and piece part consistency. This is a proposed outline on how to organize and conduct such a test.  It is the intention of the participants to publish a document, possibly an SME Technical paper or article, at the conclusion of the study.
• To see an example of some superfinishing equipment being used for the research project see:  https://www.youtube.com/watch?v=w5pyX9ix2Sw 

  GOALS: Confirm that edge and finish conditioning improves tooling life and potentially also improves performance values in tool speed, feed speed and substrate surface finish and helps prevent part surface finish deterioration from tool wear over extended periods of time.

• 

Wet Ice Crystal Blasting Overview

https://www.youtube.com/watch?v=SvySG5ZfJG4

Frequently Asked Questions

What is Ice Blasting?  (SOURCE: http://coulsoniceblast.com)

Ice Blasting is the smart solution for companies concerned with minimizing waste produced during industrial cleaning applications. Compared to other blast cleaning processes, Ice Blast reduces secondary waste by up to 95%. Ice Blasting is a simple, non-abrasive, cleaning process that capitalizes on ordinary tap water, compressed air and electricity to create an environmentally-friendly, cost effective method for tackling industrial cleaning jobs.

How does Ice Blast work?

Within 70 seconds from pushing the start button the Ice Blast machine is ready for work. Crystalline ice particles are produced continuously at a rate of 270 lbs per hour. Using a two hose system, ice particles are transported through a low pressure hose to the blasting nozzle where a second higher pressure hose delivers up to 12 bar to accelerate the ice particles towards the target surface. The solid ice particles displace surface contaminants by imparting the energy from the impact and from the lateral deformation of the ice particles. Melting after impact, the ice then flushes away the debris. This “Scrub and Flush” process is what makes Ice Blasting effective.

How does Ice Blast reduce waste?

Ice Blast uses only 27 gallons of ordinary tap water converted into crystalline ice particles per hour. Upon impact, the ice particles explode, turning approximately half of its solid mass into vapor and the other half into liquid. The amount of liquid residual for collection will vary with the relative humidity and evaporation rate of the ambient atmosphere.

How is Ice Blast different than abrasive or water blasting?

Ice Blasting does not generate dust common with most abrasive media blasting operations. This is especially important for operators involved in lead based paint or asbestos abatement jobs where airborne particulate levels must remain low. Ice Blasting is non-abrasive and will not leave a profile (*on most substrates).
Typical water blasting operations produce 90 – 600 gallons of liquid that generally needs to be contained and collected. At 27 gallons per hour there is a large cost-reduction factor in containment and disposal, especially of hazardous materials.

How is Ice Blast different than Dry Ice (CO2)?

For one, dry Ice Blasting requires the purchase of a blast media i.e. CO2. This comes in either block or pellet form that requires insulated storage and handling. Also, dry ice has a relatively short shelf life; it disappears, or loses its mass, by sublimation during transportation, storage and handling at up to 10% per day. Ice Blast does not produce CO2 during operations, making it safer to use in confined areas or where adequate ventilation is an issue.

Where do I purchase the blast media?

Blast media for Ice Blast is purchased from your local water utility company. Simply connect a ¾” water line (literally a garden hose) from your tap to the Ice Blast machine. Water is available 24 hours a day and is very inexpensive compared to purchasing blast media of any type.

Can Ice Blast strip paint?

Yes and no. Ice Blast uses the energy released upon impact to overcome a coating’s cohesive bond. If this “bond” cannot be overcome then ice alone will not be effective without the use of our ice enhancement system.

Can Ice Blast be used on wood?

Ice Blast has been used on wood successfully where lead based coatings had to be removed prior to the demolition of the structure. But, frankly speaking, wood is one of the few substrates that Ice Blast will erode. The deciding factor for using Ice Blast on afore mentioned project was Ice Blast’s low volume of waste generated (in regard to containment and collection), no blast media to purchase, worker safety features, and its ease of operation.

Can Ice Blast remove rust?

Yes and no. Because alone it is non-abrasive process, deep-seated rust is difficult to remove completely and a profile will not be generated on the substrate. We recommend either using our ice enhancement system or a rust converter primer once the loose rust has been removed.

Can Ice Blast be used on glass?

Yes. Ice Blast has been successful in removing paints, grease, oil, grime, and other contaminants from a variety of glass surfaces, including windows, gauge panels and controls. However, care must be exercised when blasting on these surfaces to avoid shattering. Typically the blast pressure is turned down and a longer stand-off is required.

Where is Ice Blast used?

Please see list of applications.

What other equipment is needed?

A source for water, air and electricity are needed to operate the Ice Blast machine. Standard water supply is ¾” potable water line normally found in all plants and facilities. Normal air supply is 175 l/s at 8 – 10 bar, however, blast pressures up to 12 bar can be used for faster cleaning rates on stubborn contaminants and coatings. Depending on the operating environment an after-cooler may be needed to keep the compressed air supply under the maximum value of 35°C. We recommend using a water separator in excessively damp or humid operating environments and/or an air filter to reduce excessive compressor blow-by.

What is the maximum operating radius of Ice Blast?

To obtain the best results, a maximum length of 70 meter of hose is used. This offers a 140 meter radius around the machine. Additionally, a maximum vertical height of 20 meter is recommended.

Can Ice Blast be used in cold environments?

Yes. Ice Blast has been successfully used outdoors in environments down to -20° C (* some additional set-up is required). If your application requires the use of Ice Blast in excessively cold areas, our service personnel will gladly provide a few simple solutions to keep the equipment running continuously.

How much regular maintenance is needed?

Not much. The unit is designed to run 24 hours per day, 7 days per week. If the operating environment is dusty we recommend cleaning the condensing coils simply by rinsing with the same water supplied to the machine.

What safety issues are there with Ice Blast?

Like all blasting type operations, worker safety should not be compromised. The system can generate up to 115 db at the nozzle when the higher velocity air meets the slower velocity ice particles. Eye and ear protection is mandatory during blasting. Respiratory protection is recommended. Protective clothing can range from simple Tyvek suits to keep general debris off the worker to full chemical gear when cleaning hazardous materials. Generally, light rain gear is used for most blasting operations. As with all blasting operations the blast nozzle should never be pointed at anyone or serious injury can occur.

 

CHANGE OF SURFACE STRESS (tensile vs. compressive)

Excerpted from SME Technical Paper MR79-569 by J. Bernard Hignett [ed. note: Harperizer and Harperized are trade names that refer to a specific OEM’s brand of centrifugal barrel finishing equ…

Source: CHANGE OF SURFACE STRESS (tensile vs. compressive)