Factors Affecting Plunge Grinding Force

Grinding force has a close relation to grinding inputs such as grinding wheel, work material, interference condition, grinding speed, grinding fluid and machine condition, and therefore varies widely with grinding inputs. On the other hand, grinding force affects significantly grinding outputs which are efficiency and quality evaluated with surface roughness, accuracy, surface integrity and so on. It is important to make clear the relations between grinding inputs and grinding force in order to control grinding outputs. In this paper, from the above point of view, the relations between grinding inputs and grinding force are experimentally investigated. It is pointed out that the normal grinding force, the tangential grinding force and its ratio are determined by the product of speed ratio of work speed to wheel speed and setting depth of cut as for interference conditions, and by the product of square of dressing feed and cutting depth of. dresser as for dressing conditions. Furthermore as for characteristics of work materials, the normal grinding force has a close relation to the yield stress, and the force ratio is related to the elongation of work material

How to combine a hydrophobic matrix and a hydrophilic filler without adding a compatibilizer – Co-grinding enhances use properties of renewable PLA-starch composites

In order to avoid the use of compatibilizers or plasticizers, co-grinding was performed to produce PLA – starch composite materials. Fragmentation and agglomeration phenomena were analysed to propose a production mechanism. Co-grinding enhances dispersion of the filler in the matrix and interactions between the materials. Consequently while blending the two materials has a negative effect on mechanical properties, co-grinding permits to improve them if optimized operating conditions are applied. Water uptake and diffusion are also controlled by co-grinding conditions. This treatment allows the production of composite materials offering good use properties without any use of a compatibilizer or a plasticizer

Damage of the Surface Layer Gears in Grinding Process.

The influence of the grinding process on the condition of the surface layer (SL) obtained by the treatment of the gear with grinding wheels Al2O3, CBN, GF, SG, alloy steels with different parameters of the grinding process and the type of cooling liquid – lubricant (CLL). The stress distribution at the surface layer, structural changes, secondary hardening, forgiveness SL and drastic damage–microcracs have been presented in comparative studies

Realization of High Efficiency and Low Damage Machining of Anisotropic KDP Crystal by Grinding

Potassium dihydrogen phosphate (KDP) is a non-linear material used in various opto-electronic applications including Q-switches, high-speed photography shutters, frequency harmonic generation lens and Pockels cells in the Inertial Confinement Fusion (ICF) devices. KDP belongs to the most difficult-to-cut material, due to its delicate and unique characteristics including the combination of softness with brittleness, anisotropic performances, tendency for deliquescence and sensitivity to temperature change. Single point diamond turning (SPDT) is considered to be the ideal method for machining KDP components. However, the process efficiency is rather low and often accompanied with severe tool wear issues. This paper studies the feasibility using grinding method to remove the surface material of KDP components with high process efficiency and low damage, fulfilling the task of re-aligning the surface orientation to the crystalline axis. The grinding tests were carried out on a common CNC grinder, using resin bonded diamond grinding wheel, whilst the diamond abrasives are coated with Ni-P alloy. The direction of precision grinding was determined by studying the anisotropy of KDP, including its elastic modulus E, Vickers hardness HV and fracture toughness KIC, to reduce the influence of material anisotropy on machining quality. The grinding process parameters were preliminarily determined based on the experimental results investigating the effects of peripheral speed of the grinding wheel, worktable feed rate and grinding depth on the ground surface roughness. The surface defects, surface morphology and sub-surface damage under different process parameters were investigated. Surface roughness Ra ≤ 0.3 μm and sub-surface damage depth SSD ≤ 6 μm were obtained. The machining efficiency can be improved by nearly ten times using the proposed precision grinding method, producing nearly the same surface quality (Ra ≤ 0.2 μm, SSD ≤ 6 μm) as that in the axis fixing phase in SPDT

The Analysis of the Cutting Forces and Surface Layer Stereometry in the Grinding Process of Abrasion-Resisting Materials

The article presents the investigation of the grinding process of flat samples made of materials that meet requirements of the lowest abrasibility, which belong to difficult to machine materials. Research enclosed measurement of cutting forces and surface layer stereometry during grinding without using cutting fluid. The tests were carried out with the aid of new generation grinding wheel, Quantum

Grinding arrangement for ball nose milling cutters

A grinding arrangement for spiral fluted ball nose end mills and like tools includes a tool holder for positioning the tool relative to a grinding wheel. The tool is mounted in a spindle within the tool holder for rotation about its centerline and the tool holder is pivotably mounted for angular movement about an axis which intersects that centerline. A follower arm of a cam follower secured to the spindle cooperates with a specially shaped cam to provide rotation of the tool during the angular movement of the tool holder during the grinding cycle, by an amount determined by the cam profile. In this way the surface of the cutting edge in contact with the grinding wheel is maintained at the same height on the grinding wheel throughout the angular movement of the tool holder during the grinding cycle

Grinding kinetics and equilibrium states

The temporary and permanent equilibrium occurring during the initial stage of cement grinding does not indicate the end of comminution, but rather an increased energy consumption during grinding. The constant dynamic equilibrium occurs after a long grinding period indicating the end of comminution for a given particle size. Grinding equilibrium curves can be constructed to show the stages of comminution and agglomeration for certain particle sizes

Submicron metal powders produced by ball milling with grinding aids

In ball milling metal powders to submicron size, various salts are more effective as grinding aids than conventional surfactants. Absolute ethyl alcohol is used as the grinding liquid

Performance of Cooled Cone Grinding Machine in Cocoa Cake Processing

The process of cocoa paste pressing has a function to separate the fatty component of cocoa from its cake. Cocoa paste is further processed into cocoa powder using grinding machine for cocoa cake. The cooled cone type of cocoa grinding machine is used to solve the problem of plug in the maschine caused by melting of fat in cocoa cake due to hot effect as a result of friction in the grinding machine. Grinding machine of cocoa has conical form of cylinder for grinding and stator wall wrapped by source of cold and closed with jacket wool. Research was conducted at Kaliwining Experimental Garden of Indonesian Coffee and Cocoa Research Institute (ICCRI) using cocoa cake containing 26.75% originated from Forastero type of cocoa seed. The capacity and recovery of the machine was influenced by space between rotor cylinder and stator wall. Grinding machine operated at cooling temperature of 25.5oC and space between rotor – stator 0.9 cm and the capacity of 187.5 kg/hour with recovery of 200 mesh cocoa powder as much as 24%. The maximum power of machine required was 2.5 kW with efficiency of energy transfer of 97%. Results of proximate analysis showed that there was no change of protein content, but protein and carbohydrate content increased after processing, i.e. from 5.70% and 59.82% into 5.80% and 61.89% respectively

Chiral Crystal Growth under Grinding

To study the establishment of homochirality observed in the crystal growth experiment of chiral molecules from a solution under grinding, we extend the lattice gas model of crystal growth as follows. A lattice site can be occupied by a chiral molecule in R or S form, or can be empty. Molecules form homoclusters by nearest neighbor bonds. They change their chirality if they are isolated monomers in the solution. Grinding is incorporated by cutting and shafling the system randomly. It is shown that Ostwald ripening without grinding is extremely slow to select chirality, if possible. Grinding alone also cannot achieve chirality selection. For the accomplishment of homochirality, we need an enhanced chirality change on crystalline surface. With this "autocatalytic effect" and the recycling of monomers due to rinding, an exponential increase of crystal enantiomeric excess to homochiral state is realized.Comment: 10 pages, 5 figure