Types Of Filtration For CNC Machines - Eclipse Magnetics

05 Jun.,2025

 

Types Of Filtration For CNC Machines - Eclipse Magnetics

In the intricate world of CNC machining, the significance of effective filtration cannot be overstated. Filtration systems play a crucial role in maintaining the health and efficiency of CNC machines by removing contaminants from cutting fluids, oils and lubricants.

Check now

This article delves into various types of filtration methods employed in CNC machines, providing insights into the workings of paper filters, cartridge filters, bag filters, and magnetic filters.

The Importance Of Filtration In CNC Machinery

CNC machines are widely used in precision manufacturing, where accuracy and consistency are paramount. These machines operate with cutting fluids and lubricants to enhance tool life, improve surface finish, and dissipate heat generated during machining processes. However, these fluids are susceptible to contamination from various sources, including metal shavings, dirt, and other particles produced during operation.

Without effective filtration, these contaminants can compromise the quality of the machining process, leading to increased tool wear, degraded surface finishes, and potential damage to machine components. Additionally, the accumulation of contaminants can adversely affect the overall efficiency and lifespan of the CNC machine.

Overview Of Different Filtration Types

To combat these challenges, various filtration methods are employed to remove unwanted particles from the cutting fluids and lubricants used in CNC machines. Each filtration type has its unique way of working, as well as its own set of advantages and disadvantages.

In this article, we will explore the intricacies of paper filters, cartridge filters, bag filters, and magnetic filters, shedding light on how each method contributes to maintaining a clean and efficient CNC machining environment, as well as discussing the pros and cons of each method.

Paper Filters

Paper filters are one of the most common types of filtration systems used in CNC machines. They typically consist of a roll or sheets of paper-like material through which the cutting fluids pass. The paper material is designed to capture and retain contaminants, preventing them from circulating back into the machining process.

In operation, the cutting fluids laden with contaminants flow through the paper filter. As the fluids pass through the porous paper, particles such as metal shavings and debris are trapped on the filter's surface. The clarified fluid then continues its circulation within the CNC machine, promoting a cleaner and more efficient machining process.

Advantages Of Paper Filters

  1. Cost-effective

Compared to some other filtration methods, paper filters are often more economical, making them an attractive choice for certain applications.

  1. Readily Available

Paper filters are widely available, making them easy to obtain. This means that you have a wide range of choice when it comes to manufacturers and types of paper filter.

Disadvantages Of Paper Filters

  1. Limited lifespan

Paper filters can have a relatively short lifespan, especially in high-volume machining environments, requiring frequent replacements.

  1. Prone To Blockage Or Breakage

In intensive machining operations, paper filters may clog faster, necessitating more frequent monitoring and replacement. They may also tear under heavy use, allowing contamination to flow through the filter medium.

  1. Sustainability Concerns

Paper filters contribute to environmental waste due to their disposable nature. The constant need for replacement adds to the accumulation of discarded filter materials, raising sustainability concerns. There is a risk of excessive landfill from using these filters.

  1. Maintenance Requirement

 While paper filters are generally easy to replace, the frequent need for maintenance and replacements can lead to downtime in CNC operations. This can impact productivity and increase operational costs associated with labour and machine idleness.

  1. Small Particles Able To Pass Through

Despite their efficiency in capturing fine particles, some paper filters may allow smaller particles to pass through, compromising the overall filtration effectiveness. This can result in the continued presence of contaminants in the cutting fluids.

Cartridge Filters

Cartridge filters are another prevalent filtration method in CNC machining. These filters employ cylindrical cartridges made of various materials, including paper, fabric, or metal, to capture and retain contaminants present in cutting fluids.

The operation of cartridge filters involves the flow of contaminated cutting fluids through the cylindrical cartridges. As the fluid passes through the filter media, contaminants are trapped, and the clarified fluid proceeds through the CNC machine.

Cartridge filters are known for their extended lifespan when compared to paper filters, making them suitable for applications with moderate to heavy machining demands.

Advantages Of Cartridge Filters

  1. Longer Lifespan

Cartridge filters typically have a longer lifespan than paper filters, reducing the frequency of replacements and associated downtime.

  1. Increased Filtration Efficiency

The design and materials of cartridge filters often result in improved filtration efficiency, capturing a broader range of particle sizes.

  1. Variety Of Filter Media Options

Cartridge filters offer versatility in filter media options, allowing users to choose materials based on specific machining needs. This adaptability enhances their effectiveness in capturing a diverse range of contaminants.

Disadvantages Of Cartridge Filters

  1. Higher Initial Cost

Cartridge filters may have a higher initial cost compared to paper filters, requiring a larger upfront investment.

  1. May Require More Maintenance

While cartridge filters last longer, they may require more intricate maintenance procedures, such as periodic cleaning or replacement of filter elements, which could increase operational complexity.

  1. Potential for Increased Energy Consumption

Depending on the design and size of the CNC machine, the use of cartridge filters may lead to increased energy consumption. This is especially relevant if the machine's pump must work harder to circulate fluids through the denser filter media.

  1. Complexity in Changing Filter Media

While cartridge filters offer adaptability, changing filter media types can be more complex than replacing entire paper filters. This complexity may require additional training or expertise, impacting maintenance procedures.

  1. Environmental Impact And Sustainability

Cartridge filters, like their paper counterparts, contribute to environmental concerns due to the disposal of used filter elements. There is a risk of excessive landfill from using these filters. The materials used in some cartridges may be non-biodegradable, adding to the overall environmental footprint. Proper disposal methods or recycling options must be considered to mitigate these sustainability challenges.

Bag Filters

Bag filters, a distinctive filtration method, utilise a bag-shaped filter medium to capture and retain contaminants from cutting fluids in CNC machines. These filters are designed to accommodate a wide range of particle sizes and are commonly employed in various machining applications.

The functionality of bag filters involves the flow of contaminated cutting fluids through the bag-shaped filter. The bag captures particles, preventing them from re-entering the machining process. Bag filters are known for their high dirt-holding capacity and are suitable for applications where larger volumes of contaminants are expected.

Advantages Of Bag Filters

  1. Increased Capacity

Bag filters excel in holding a large volume of contaminants, reducing the frequency of replacements and minimising downtime.

  1. Cost-Effective

In scenarios with significant contamination levels, the cost-effectiveness of bag filters becomes evident as they can handle larger quantities of debris without rapid clogging.

Disadvantages Of Bag Filters

  1. Limited Fine Particle Filtration

While effective for larger particles, bag filters may not provide the same level of filtration for fine particles as some other methods. This limitation could impact the overall cleanliness of the cutting fluids.

  1. Prone to Tearing Or Damage

The bag filter material is susceptible to tearing or damage, especially in high-stress machining environments. This vulnerability may result in the release of contaminants and compromise the filtration process.

  1. Environmental Impact

Like paper and cartridge filters, the disposal of used bag filters raises environmental concerns. The non-biodegradable nature of some filter materials contributes to the accumulation of waste, necessitating proper disposal practices for sustainability. 

Magnetic Filters

Magnetic filters provide a unique approach to CNC machine filtration by leveraging magnetic fields to capture ferrous particles from cutting fluids. These filters are designed to attract and retain metal contaminants, enhancing the cleanliness of the fluid used in machining processes.

Magnetic filters function through the application of magnetic fields within the CNC machine. As the cutting fluid passes through the magnetic filter, ferrous particles are magnetically attracted and held onto the filter's surface. This process effectively removes metal contaminants, preventing their circulation back into the machining process.

By capturing ferrous contamination and holding it with magnetic force, some of the non-magnetic contamination may also be trapped amongst the collected ferrous contamination to provide a degree of extra capture (depending on the application).

It is always recommended to place a magnetic filter before any other filter type. This allows the magnet to capture as much as possible, so the other filter has less to capture prolonging its life significantly.

Advantages Of Magnetic Filters

  1. Effective Removal Of Ferrous Particles

Magnetic filters are capable of removing ferrous particles at a sub-micron level. This is superior to all barrier methods of filtration, ensuring the removal of metal contaminants that could otherwise compromise the CNC machining process.

  1. Low Maintenance

Magnetic filters typically require minimal maintenance compared to other filtration methods. Manual systems require periodic cleaning, whilst automated systems require minimal maintenance (e.g. systems with 24 hour operation with automated cleaning cycles). The magnet filter is not a consumable – just clean and re-use.

  1. Sustainability Benefits

Magnetic filters can offer sustainability advantages by promoting a cleaner and more efficient machining process. With reduced reliance on disposable filter media, there is less environmental impact, making magnetic filtration a potentially more sustainable option in the long run.

Contamination collected by a magnetic filter is easily cleaned off to allow for recycling back into the production chain to make new product, rather than being sent to landfill. If you don’t need to replace the other filters, less waste ends up in landfill and less is spent on such consumables. And, with longer intervals between changing the other filters, using automated magnetic filters can reduce maintenance downtime costs.

A cleaner system may also prolong intervals between fluid changes, providing additional environmental and cost benefits. In light of a global need to reduce carbon footprint to help protect our planet, magnetic filters offer means improving material consumption with improved recycling possibilities.

Xuda Filtration supply professional and honest service.

  1. Energy Efficiency

Magnetic filters generally have lower energy consumption compared to some other filtration methods. The absence of power-hungry pumps or complex filter media systems contributes to a more energy-efficient CNC machining setup.  A non-automated magnetic filter requires no power to operate.

  1. No-Block Design

Magnetic filters are designed with features to prevent blockages. This means that even if the filter reaches its collection capacity, the fluid continues to run through the filter without blocking or causing excessive pressure drops. This helps to reduce the risk of unplanned downtime.

  1. Cost Savings

The ferrous contamination that is collected can be more easily sold back to recyclers rather than contamination stuck within other filter media risking being sent to landfill. 

With less consumables used, and an extended interval between filter changes, fluid changes and maintenance work, the cost of a magnetic system starts to be offset by those cost savings. In applications with heavier contamination, the return on investment may start to happen more quickly.

Disadvantages Of Magnetic Filters

  1. Limited To Ferrous Particle Removal

While highly effective for ferrous particles, magnetic filters may not capture non-ferrous contaminants (other than that which may have become trapped between the ferrous contaminants). This limitation necessitates supplementary filtration methods for comprehensive contaminant removal.

  1. Initial Cost

The initial investment for magnetic filtration systems may be higher than some traditional filter types. However, the long-term benefits and reduced maintenance costs may offset the initial expense over time.

Comparison Table

Paper Filter

Cartridge Filter

Bag Filter

Magnetic Filter

Initial Investment

Low

Low

Low

Medium - High

Collection Capacity

Low

Medium

Medium

High

Collection Material

Ferrous and non-ferrous

Ferrous and non-ferrous

Ferrous and non-ferrous

Ferrous only

Lifespan

Shorter

Medium

Medium

Long

Sustainability

Disposable

Disposable

Disposable

Reusable

In Summary

In the intricate landscape of CNC machining, the choice of filtration method significantly influences the efficiency, precision, and sustainability of the overall process. Each filtration type brings a unique set of advantages and challenges to the table.

Paper filters, while cost-effective and efficient at capturing fine particles, come with limitations in lifespan and environmental sustainability. Cartridge filters offer extended service life and superior filtration but may pose higher upfront costs and maintenance complexities. Bag filters stand out for their high dirt-holding capacity, yet they may fall short in fine particle filtration and are susceptible to damage.

On the other hand, magnetic filters provide an innovative solution with effective ferrous particle removal, low maintenance requirements, and potential sustainability benefits. While each filtration type has its strengths and weaknesses, the choice ultimately depends on the specific requirements and priorities of the CNC machining operation.

For many applications, a magnetic filter will complement the existing filter systems, enhancing filtration performance, reducing consumable usage, and extending maintenance intervals.

As CNC technology continues to advance, the quest for optimal filtration methods persists. Balancing factors such as filtration efficiency, maintenance needs, initial costs, and sustainability considerations will guide machine operators toward the most suitable filtration solution for their unique machining environment.

By understanding the nuances of each filtration type, CNC professionals can make informed decisions to enhance the performance and longevity of their equipment, while minimising environmental impact.

If your fluids contain ferrous contaminants and you consume a lot of filters annually, by simply adding a magnetic filter before your existing filter systems, you will start to gain benefits including reduced consumable usage, less landfill usage, improving carbon footprint and long-term cost savings. Some of these can be easily measured and tracked for clear return on investment. Now ask yourself, “Why wouldn’t I want to consider a magnet filter in my system?”

Are you interested in learning more about Press filter paper supplier? Contact us today to secure an expert consultation!

Plate and filter press.pptx - SlideShare

Recommended

FILTRATION-Plate and frame filter press FILTRATION-Plate and frame filter press sruthi's Pharma World The document describes the plate and frame filter press. It has the following key points: 1. It uses surface filtration where slurry enters the frame under pressure and flows through the filter medium, with filtrate collected on the plates. 2. It is made of plates and frames, usually of aluminum alloy, with studded or grooved plates to support the filter cloth. 3. Multiple plates and frames are arranged in parallel to increase filtration rate, with inlet and outlet channels connecting the plates and frames. 4. It operates in two steps - filtration where cake is formed, and washing using additional wash plates and channels to efficiently wash the entire cake surface.CENTRIFUGATION-Semi continuous centrifuge CENTRIFUGATION-Semi continuous centrifuge sruthi's Pharma World This document describes the principles, construction, and working of a semi-continuous centrifuge. It consists of a vertical perforated basket that rotates horizontally to separate solids from liquids in a slurry based on density differences. The solid cake builds up inside the basket until it reaches a certain thickness, at which point the slurry inlet stops. The cake is then washed, rotated for a period of time, and a hydraulic knife lifts to cut the cake but leaves a thin layer behind to act as a filter for the next cycle. This process allows for continuous and automated separation of solids from liquids in batches.Filtration, Drum filterFiltration, Drum filtersruthi's Pharma World The document discusses a drum filter, which is a surface filtration device used to filter slurries. It consists of a horizontally mounted, perforated metal cylinder that is 3 meters in diameter and 3.5 meters long, providing 20 square meters of surface area. As the drum rotates, slurry is deposited on the perforated surface and a vacuum pulls liquid through the filter cloth, leaving a solid cake that is continuously removed. Drum filters can filter concentrated slurries continuously at low labor cost due to their large surface area and ability to control cake thickness by varying rotation speed.Filter press and shell and leaf filtersFilter press and shell and leaf filtersKarnav RanaThis document discusses different types of industrial filtration equipment, including plate and frame filter presses and shell and leaf filters. Plate and frame filter presses operate in batches, using increased pressure to maximize filtration rates. They consist of alternating plates and frames that form chambers for filter cakes. Shell and leaf filters use a set of vertical leaves in a horizontal tank, applying pressure to force slurry through the leaves, leaving filter cake on the outside. They provide a large surface area and are suitable for filtrations requiring filter aids.Filter leaf Filter leaf sruthi's Pharma World The document summarizes the filter leaf, which is an apparatus used for surface filtration. It consists of a frame enclosing a drainage screen or grooved plate covered with a filter cloth. Vacuum is applied to increase the filtration rate. Filter leaves are versatile, provide a simple form of batch filtration, and can be connected in parallel to increase surface area. They are used to filter dilute suspensions around 5% solid content. Advantages include simplicity, moderate labor costs, and high washing efficiency.FiltrationFiltrationritu kudarhaThis document provides an overview of filtration, including definitions, terms, processes, mechanisms, theories, factors influencing filtration, filter media, filter aids, classifications of filtration equipment, and plate and frame filter presses. Filtration is defined as the separation of solids from fluids by passing them through a porous medium. Key points covered include common filtration mechanisms like sieving and straining, Darcy's and Kozeny-Carman equations describing filtration rates, and factors like pressure, surface area, viscosity, and properties of solids and liquids. Common filter media like woven materials, membranes, and granular solids are also described.CrstallizationCrstallizationElambaruthi ElambaruthiCrystallization is a process where a solid forms from a liquid solution as atoms or molecules organize into a crystal structure. Crystals can form through precipitation, freezing, or deposition from a gas. The attributes of the resulting crystal depend on factors like temperature, pressure, and fluid evaporation time. Crystallization separates solutes from a solution by forming solid particles. It involves mass transfer from the liquid phase to the crystal surface. Continuous crystallizers like the Swenson-Walker crystallizer operate on a cooling and super saturation principle to continuously form crystals of uniform size and free of inclusions from the liquid feed.Sigma blade mixerSigma blade mixerGoodu Mastan Vali ShaikSigma Blade mixer is a mixing equipment used for the mixing & kneading of high viscous food materialsRotatory drum vacuum filterRotatory drum vacuum filterTechQaisarThe document summarizes the key components and functioning of a rotatory drum vacuum filter. It consists of a sheet metal drum divided into sections covered with a filter cloth. Liquor is sucked through the filter cloth onto the rotating drum to deposit a cake of solids. As the drum rotates, the cake moves through different zones - first forming in the filtration zone, then being washed and dried before the cake is removed in the removal zone by a doctor knife. Various methods are used to discharge the cake, including scrapers, belts, pre-coat, rolls or strings depending on the cake properties. It is widely used in industrial processes that require continuous large-volume solid-liquid separation.FiltrationFiltrationProf. Dr. Basavaraj NanjwadeThe document discusses various aspects of filtration including definitions, applications, factors affecting filtration, theories of filtration such as Darcy's law and Kozeny-Carman equation. It also describes different types of filtration equipment used in the pharmaceutical industry such as filter presses, membrane filters, filter candles and sintered filters. Continuous filters are also discussed which involve continual washing of filter media.DryingDryingsahebrao BorasteDrying is defined as the removal of water or other liquids from a material through the application of heat. It involves three steps: heat transfer to the material, mass transfer of moisture to the surface and evaporation, and transfer of vapor away from the material. There are several theories that describe the drying mechanism, including diffusion, capillarity, and pressure gradient theories. The drying rate curve shows an initial adjustment period, constant rate period, falling rate periods, and an equilibrium moisture content where drying stops. Factors like material properties, air conditions, and particle size influence the drying process and rate.Sigma blade mixerSigma blade mixerAbhijit PanchmatiyaThe sigma blade mixer consists of a double trough shaped stationary bowl with two sigma shaped blades fitted horizontally in each trough. The blades are connected to a fixed speed drive and rotate to create high shear and kneading actions through their intermeshing motion. Powders are introduced into the trough from the top and the body is covered during mixing to prevent dust or evaporation. The sigma blade mixer is commonly used for mixing dough ingredients through its ability to thoroughly blend materials with minimal dead space at a fixed speed.Filtration by ankita yagnikFiltration by ankita yagnikAnkita YagnikThis document discusses filtration, which is defined as the separation of solids from liquids by passing the mixture through a porous medium. It describes different types of filtration including surface and depth filtration. Key factors that affect the filtration rate are also outlined. Various filter media are discussed, along with theories of filtration like Poiseuille's equation and Darcy's equation. Finally, common industrial filters used in pharmaceutical industries like filter presses and rotary filters are briefly introduced.FitrationFitrationYogeshwary Bhongade- Filtration Objectives, applications, Theories & Factors influencing filtration, filter aids, filter medias. Principle, Construction, Working, Uses, Merits and demerits of – Plate & frame filter, Filter leaf, Rotary drum filter, Meta filter Cartridge filter, Membrane filters & Seidtz Centrifugation-Non perforated basket centrifuge Centrifugation-Non perforated basket centrifuge sruthi's Pharma World This document describes a non-perforated basket centrifuge, which separates solids from liquids using centrifugal force without a porous barrier. It consists of a non-perforated basket suspended on a vertical shaft that is spun by a motor. During centrifugation, the heavier solids are retained on the basket walls while the lighter liquid rises to the top and is removed via a skimming tube. It is used when deposited solids impede liquid flow more than in centrifuges with porous barriers.CentrifugationCentrifugationYogeshwary BhongadeObjectives, principle & applications of Centrifugation, principles, construction, working, uses, merits and demerits of – Perforated basket centrifuge, Non-perforated basket centrifuge, Semi continuous centrifuge & Super centrifuge. Filtration, cake filters & principles of cake filtration Filtration, cake filters & principles of cake filtration Karnav RanaThis document discusses filtration and cake filtration principles. Filtration is the separation of solids from a liquid suspension using a porous medium. In cake filtration, the suspended solids build up on the filter medium over time, forming a thicker cake with higher resistance. As the cake builds, the filtration rate decreases unless more pressure is applied. Common cake filters include filter presses, belt filters, and various types of vacuum filters that use a building cake to separate solids from liquids.ELUTRIATION METHOD.pptxELUTRIATION METHOD.pptxKashishWilson1The elutriation method separates particles based on size, shape, and density using a stream of gas or liquid flowing in the opposite direction of sedimentation. Fine particles remain suspended due to their low density, while coarse particles settle due to their high density. The process involves mixing a powder sample with water in an elutriation tank, allowing particles to settle or remain suspended based on density, and collecting fractions from outlets at different heights as the sample is withdrawn. Modern elutriation uses a column with inlets, outlets, and overflows to separate particles into fractions based on the decreasing fluid velocity in connected columns of increasing cross-sectional area. The method provides a continuous, quick separation into multiple fractions using compact apparatus15 crystallization15 crystallizationUniversity of Zambia, School of Pharmacy, Lusaka, ZambiaThis document provides an overview of crystallization as a separation and purification technique. It discusses key concepts such as crystallization, nucleation, crystal growth, and factors that affect crystallization. Specifically, it describes three steps of crystallization from solution: induction of supersaturation through methods like cooling, solvent evaporation, or adiabatic evaporation; nucleation through Miers' theory; and crystal growth which depends on concentration, temperature, and velocity gradients. It also discusses methods of controlling crystal size and factors that influence the crystallization process like temperature, impurities, and agitation.MixingMixingYogeshwary BhongadeObjectives, applications & factors affecting mixing, Difference between solid and liquid mixing, mechanism of solid mixing, liquids mixing and semisolids mixing. Principles, Construction, Working, uses, Merits and Demerits of- Propellers, Turbines, Paddles Double cone blender & Twin shell blender Ribbon blender Sigma blade mixer Planetary Mixers Silverson Emulsifier Centrifugation by ankita yagnikCentrifugation by ankita yagnikAnkita YagnikCentrifugation is a process that uses centrifugal force to separate particles in suspension based on density differences. It works by spinning the suspension at high speeds, causing heavier particles to settle faster than lighter ones. There are several types of centrifuges that can be used including filtration, sedimentation, and continuous centrifuges. Filtration centrifuges separate particles through a perforated basket, sedimentation centrifuges separate in a solid walled vessel, and continuous centrifuges allow for high throughput separation. Key factors that affect centrifugation include liquid properties, particle characteristics, operating parameters, and centrifuge design features.Pharmaceutical Engineering: CentrifugationPharmaceutical Engineering: CentrifugationParag JainObjectives, principle, application of centrifugation, perforated basket centrifuge, non-perforated basket centrifuge, semi-continuous centrifuge, super centrifuge membrane filtrationmembrane filtrationAnkit SharmaThis seminar discusses membrane filtration processes used for drug product sterilization. It introduces various types of membrane filtration including microfiltration, ultrafiltration, reverse osmosis, and gas separation. Validation of membrane filters is also covered, outlining testing for reproducibility, sterilization integrity, microbial challenges, and endotoxins. The presentation emphasizes that validation is necessary to ensure membrane filters consistently produce safe, effective products meeting quality standards.MOLECULAR DISTILLATION.pptxMOLECULAR DISTILLATION.pptxsruthi's Pharma World Molecular distillation is a distillation process that occurs under high vacuum conditions. This allows molecules to travel through the vapor phase without intermolecular collisions before condensing individually on a nearby surface. There are two main types of molecular stills - falling film stills and centrifugal stills. Falling film stills use a heated surface and wipers to create a thin liquid film for evaporation, while centrifugal stills rotate a bucket at high speeds to create an evaporating liquid film on the inner wall. Both utilize a short path between evaporation and condensation surfaces to minimize molecular collisions in the vapor phase. Molecular distillation is useful for separating compounds with similar boiling points.FiltrationFiltrationPharmacy UniverseFiltration is a physical, biological or chemical operation that separates solid matter and fluid from a mixture with a filter medium that has a complex structure through which only the fluid can passROTARY DRUM FILTER, DISK CENTRIFUGE AND MICROFILTRATIONROTARY DRUM FILTER, DISK CENTRIFUGE AND MICROFILTRATIONHimanshuKhadatkardescribing working, principle and construction of rotary drum filter, disk centrifuge, microfiltrationSize reduction by ankita yagnikSize reduction by ankita yagnikAnkita YagnikThis document discusses size reduction, which is the process of reducing larger particles into smaller particles of a desired size and shape using external forces. It defines size reduction and comminution, and lists the objectives of size reduction such as increasing surface area and achieving intimate mixing. The document describes various size reduction mechanisms, factors affecting size reduction, and theories related to the energy required. It provides details on different size reduction equipment like hammer mills, ball mills, fluid energy mills, edge runner mills, and end runner mills.