This invention relates to continuous metal casting systems, and more particularly to lubricating systems for automatic grease lubrication of a casting mould surface. Background Art

Casting moulds are used to shape molten metal and to extract heat from the metal to form a solid casting or ingot. These moulds have two basic characteristics. The first is to extract heat to effect solidification, and the second is to provide a parting agent or lubricant to prevent adherence between the molten metal and the mould. The distribution of the lubricant over the surface of the inner mould wall has a substantial effect on the surface quality of the ingot.

Lubricated moulds are typically used in vertical direct chill (D.C.) casting systems with or without insulated or hot tops and in horizontal casting systems. Direct chill casting is widely used for the casting of aluminum and other like metals and in this system, the molten metal is poured into the inlet end of an open ended mould while liquid coolant is applied to the inner periphery of the mould to maintain heat transfer thereby initiating solidification of the metal as an ingot. Also, the same or a different coolant is normally applied to the exposed surface of the ingot as it emerges from the outlet end of the mould to continue the cooling effect on the solidified metal. A typical example of a direct chill casting mould is that described in Wagstaff, U.S. Patent 4,421,155 issued December 20, 1983. Other examples include Harrington et al., U.S. Patent 3,612,151 and Bryson, U.S. Patent 3,713,479.

It is also commonplace in D.C. casting to use a lubricating oil as parting agent or lubricant on the mould surface. The oil is typically castor oil, rapeseed (Canola) oil, other vegetable or animal oils, esters, paraffins, synthetic liquids, etc. A problem with the use

paraffins, synthetic liquids, etc. A problem with the use of oil as a lubricant is that substantial amounts are required to achieve uniform distribution and it is difficult subsequently to separate the oil from the cooling water used in D.C. casting.

Lubricant feeding systems of this type generally use feeder plates or similar apparatus located generally above the coolant channels in the DC mould so that lubricant can be effectively applied where required. The feeder plates may be separate devices or be an integral part of the mould construction. It is difficult to feed grease through such devices within the present design of the plate and mode of operation since the grease generally changes from solid to liquid within the feeder plate and the consequent rheological change makes control of grease distribution difficult.

U.S. Patent 4,917,171, issued April 17, 1990, describes a lubricating system for a continuous casting mould in which a meltable lubricant, e.g. grease, is injected through orifices in the peripheral wall of the mould. The lubricant is fed from the outside of each orifice independently, necessitating either a very small number of orifices and thus poor distribution or a large number of orifices and an unacceptably expensive system. It is also common to apply grease manually. However, this process is generally not acceptable for aggressive alloys or for long ingot lengths. Also, with manual application there is no control over the amount of lubricant used and re-application while casting is in progress constitutes a safety hazard.

Particularly with direct chill casting where cooling water is sprayed onto the surface of the emerging ingot and flows down into a collection sump, there is today a serious problem in the disposal of the coolant water contaminated by the lubricant. Thus, before the cooling water can be discharged, the lubricant content must be substantially reduced. Depending on the local

regulations, discharge levels can be as low as 5 ppm for natural lubricants (e.g. vegetable or animal based) or even lower for synthetic lubricants (e.g. mineral oil based) . This generally requires large and expensive separator systems, and it is considered advantageous to consequently reduce the input of lubricant as much as possible.

It is an object of the present invention to provide an improved lubricant delivery system which permits the use of a grease as lubricant in continuous metal casting in as effective a manner as oil.

It is a further objective of the present invention to provide an important lubricant delivery system which permits the use of less grease lubricant (expressed as consumption per length of cast product) than oil lubricants.

Disclosure of the Invention

The present invention relates to a process and apparatus for casting molten metal. The apparatus comprises a mould for effecting solidification of the molten metal into a formed metal product, means adjacent to an inlet portion of the mould for feeding the molten metal into the mould and means for delivering a lubricating grease to a surface of the mould contacting the molten metal to substantially prevent adhesion of any solidified metal on the surface.

The term "grease" as used herein is intended to indicate a lubricant which is solid at ambient temperatures and which readily melts into liquid form with heating. The grease may be of an animal, vegetable or mineral (synthetic) source and for environmental reasons animal or vegetable based greases are preferred. For instance, vegetable shortening or lard used in baking are well suited for use in this invention. The grease delivery system of the present invention basically includes at least one lubricant delivery channel arranged generally parallel to the mould surface. Inlet

means are provided for delivering a flow of grease under pressure into the delivery channel and a plurality of small flow passages extend between the delivery channel and the mould surface for delivering grease in liquified form from the channel to the mould surface. When the mould is operational, the grease within the delivery channel is normally in liquified form and flows either under pressure or by gravity from the delivery channel through the small delivery passages to the mould surface. The grease may be liquified while contained within the delivery channel or it may be liquified prior to entering the delivery channel. The liquifying may take place because of heat input within the mould itself or the heating may be carried out externally of the mould. One preferred embodiment of the novel grease system of the present invention includes at least two grease delivery channels arranged generally parallel to the mould surface. These delivery channels are generally laterally spaced from each other and connected to neighbouring channels by a plurality of restrictive flow passages. Grease is injected into the first of such delivery channels and flows via the restrictive flow passages to the next delivery passage. A final set of restrictive flow passages connects the final such delivery channel to the mould face and delivers the grease to the mould face in the desired location.

The restrictive flow passages have high resistance to flow compared to the delivery channel immediately upstream of the flow passages, and in this manner the flow of grease from one grease delivery channel to the next, and finally to the mould face is maintained uniform. Uniformity is maintained provided that the pressure drop across the restrictive flow passages is at least 10 times and preferably 20 times the static pressure drop in the delivery channel immediately upstream.

Typically, restrictive flow passages which feed grease to the mould face are shorter and more closely

spaced than such passages further upstream, but any combination of diameters, lengths and spacings, consistent with the criteria above may be selected. In practice, the restrictive flow passages which feed grease to the mould face are sized and located first for operation requirements, then the above criteria are used to size the preceding delivery channel and so on back to the original grease delivery point. Methods of calculation as disclosed in Leblanc & Newberry, U.S. Patent 5,044,535, issued 23 July 1991 and incorporated herein by reference, may be used for this purpose.

During casting, the final delivery channel closest to the mould face contains the grease in liquid form and this channel may either be closed to the atmosphere and pressurized or it may be open to the atmosphere by way of top vents such that the liquified grease flows by gravity from the channel through the delivery passages to the mould surface. When the system is operated in the gravity feed mode, sufficient liquified grease is added to the final channel closest to the mould face to supply a complete casting procedure. Flow rates are determined by the number of lubricant outlets, the size of the lubricant outlets, the viscosity of the liquified grease and the static head pressure at the lubricant outlets. Flow rates cannot be regulated for the gravity feed system as they can be for a pressurized system.

The delivery channel or channels and the flow passages may be formed within a distribution plate positioned above the mould or partially in a distribution plate and partially within the mould itself or entirely within the mould itself. It has been shown to be advantageous to provide for temperature control within the grease distribution plate. In one embodiment of the distribution plate, it is placed on top of and insulated from the mould and separate heating means such as channels for heating fluid or electrical heating elements are provided within the distribution plate. The insulation

serves to isolate the distribution plate from the coolant channel and may also be placed in other locations, for example in the top of the water channel itself. This means that the temperature of the distribution plate can be controlled independently of the temperature of the mould itself and this assures uniform temperature within the distribution plate thereby enhancing the uniformity of grease distribution at the lubricant outlets. Another advantage of the independent temperature control lies in ensuring that the mould face over which the liquid grease flows is maintained at an appropriate temperature to allow the grease to cover the surface uniformly.

In another embodiment using a separate heating means, the heating may be provided by a fluid (for example, steam, water, ethylene glycol, etc) which is heated externally to the mould and pumped through channels incorporated into the grease distribution plate. The fluid flow and channel location may be designed for improved temperature uniformity. By provision of a means of either heating or cooling the fluid, or by providing separate heated and cooled fluids to the same channels via a system of valves, it is also possible to cool the grease sufficiently that it will no longer flow readily. This is particularly advantageous when the casting operation has been completed and it is desired to prevent the residual grease from flowing out of the channels within the mould. In another embodiment using a distribution plate, it is mounted directly on top of the mould without any intervening insulation and an upstream distribution channel is formed within the distribution plate. The final distribution channel is formed within the mould itself as are the intermediate and final sets of flow passages. This arrangement is highly dependent upon the material of the mould and the top manifold plate, as well as the immediate atmosphere for determining the temperature of the grease. The efficiency of this embodiment is directly related to the distance of the

lubricant outlet from the molten metal, details of which are shown in Example 2 below. The temperature control in the grease distribution system in this embodiment can also be modified to a certain extent through the use of thermal insulation, for example, located on the interior surface of the coolant channel nearest the lubricant distribution channels. This provides for the creation of temperature profiles in the grease distribution channels and on the mould face different from those that would be established by the coolant channel alone and hence allow better control over grease flow.

Grease can be added to the delivery channels by a number of means. It can be fed continuously or intermittently (for example in the form of repetitive pulses) . Intermittent feed has a particular advantage in that overall grease consumption is reduced. This is due to the surprising improvement in grease distribution uniformity that is achieved by feeding at a higher rate at intervals over feeding at a low rate continuously. There are a number of possible explanations for this, including the improved flow characteristics of grease under pulsed conditions due to shear thinning, or to improved heat transfer to the grease, or to improved flow on the mould face. According to yet another embodiment of the invention, a grease recirculating system is provided externally of the mould. This recirculating system is connected to a preferably low thermal conducting distribution plate positioned on top of the mould and the grease in the recirculating system is preferably heated in the grease reservoir. With this arrangement, there are two flow arrangements, the first being a recirculating arrangement in which the grease is simply circulated while passing through the distribution plate and a second flow arrangement in which the recirculating heated grease is discharged through the distribution plate via at least one grease channel contained in the plate and flow passages

extending across between the channel and the mould surface.

The grease delivery system of this invention may be used with moulds for a variety of ingot shapes, including extrusion and sheet ingot, with or without insulated or hot tops. It is of particular value with a casting device having a mould with an inner, axially extending wall defining a mould cavity, e.g. a direct chill casting system. One of the important advantages of this invention is that the grease frequently has viscosity-temperature relationships which permit much smaller quantities to be used in systems of this invention than lubricating oils in equivalent continuous systems. This requires less cleanup of casting water before discharge into the environment to meet local environmental regulations.

Brief Description of the Drawings

The invention will be more fully understood from the following description of embodiments thereof, given by way of example only, with reference to the accompany drawing, in which:

Figure 1 is a perspective view of a typical peripheral direct chill casting mould;

Figure 2 is a simplified sectional elevational view of a direct chill casting apparatus;

Figure 3 is a sectional view of a grease delivery plate according to the invention;

Figure 4 is a sectional view of a further grease delivery plate according to the invention; Figure 5 is a sectional view of yet another grease delivery plate according to the invention;

Figure 6 is a sectional view of a direct chill casting mould showing a modified grease distribution syste ; Figure 7 is a sectional view of a direct chill casting mould showing a further modified grease delivery system;

Figure 8 is a sectional view of a direct chill casting mould showing a further modified grease distribution system;

Figure 9 is a sectional view of a direct chill casting mould showing a further modified grease distribution system;

Figure 10 is a schematic flow diagram of an external grease recirculating system;

Figure 11 is a schematic flow diagram of an external fluid heating/cooling system;

Figure 12 is a plan view of a flow circuit of the invention;

Figure 13 is a plan view of another flow circuit of the invention; Figure 14 is a plot of lubrication consumption v. mould temperature; and

Figure 15 is a plot of lubrication consumption v. distance from the lubricant outlet.

Best Modes For Carrying Out the Invention The device shown in Figures 1 and 2 is a mould assembly having an open ended rectangular body configuration. The mould 10 has a vertical mould face 11 which comes into contact with the molten metal. A coolant manifold 12 is fed with coolant for the purpose of cooling the mould surface 11. For casting an ingot, molten metal 15 is fed via dip tube 14 into the mould and the metal is chilled sufficiently to form an outer skin while passing the mould plate wall face 11. The ingot thus being formed is then further cooled by water sprays 13. The ingot 30 being formed is supported by a stool 31 which moves downwardly and controls the casting rate. The forming ingot moves downwardly into a pit (not shown) and the bottom of the pit includes a sump for collecting the coolant 13 sprayed onto the surface of the ingot 30. One embodiment of the lubricating system of this invention is illustrated in Figure 3 and is intended to provide a uniform distribution of grease on the mould face

under casting conditions. In the embodiment of Figure 3, a grease distribution plate 16, comprising an upper portion 16a and a lower portion 16b, is positioned on top of mould 10. This distribution plate includes an inner edge face 17, a top face 18 and a bottom face 19. A layer of insulation 25 is provided between the bottom 19 of plate 16 and the top face of mould plate 10. The inner edge face 17 includes a downwardly projecting lip 26 which ensures that the molten grease flows past as few corners as possible thus making the meniscus as uniform as possible. At the same time it protects the insulation 25 from the lubricant and from any direct contact with molten metal. The inner face 17 and lip 26 merge into the mould face 11. The distribution plate 16 includes a large primary grease channel 20 extending generally parallel to the distribution plate face 17 and mould face 11 and remote therefrom. Grease is fed into channel 20 by a grease pump (not shown) through an inlet connector (not shown) . A secondary delivery channel 23 of smaller cross-sectional dimension is positioned spaced from primary channel 20 and also spaced a short distance from distribution plate inner edge 17. A plurality of restrictive passages 21 extend across between channels 20 and 23. A plurality of small restrictive delivery passages 24 extend from channel 23 to face 17.

Heating elements 28 are mounted within plate 16 and extend generally parallel to face 17. They are held in contact with plate 16 by means of springs or gasketting 27. These heating elements provide uniform heating of the channels 20 and 23 as well as the restrictive passages 21 and the delivery passages 24.

In the particular embodiment shown in Figure 3, the distribution plate 16 consists of an upper portion 16a and a lower portion 16b joined by threaded studs (not shown) and O-ring seals 29. With this arrangement, the delivery passages 24 are in the form of grooves formed either in

the bottom face of upper plate portion 16a or in the top face of lower plate portion 16b.

In the embodiment of Figure 4, a lubricating plate 66 is positioned on top of a mould 65 with a layer of insulation 67 therebetween. The outer edge of the insulation 67 is protected by means of a downwardly projecting lip portion 66a of plate 66 providing a smooth transition between the grease plate and the mould face. Positioned above the plate 66 is a grease distribution plate 68. This plate has a primary distribution channel 70 and a secondary distribution channel 69 formed therein. A horizontal bore 71 extends inwardly from one edge of plate 68 and is closed by means of plug 72. This bore is connected to the upper end of distribution channel 70 and has a restriction zone 73 therein. The inner end of this restriction zone connects to a further bore 74 extending upwardly from secondary channel 69. A set of restrictive flow passages 78 extend from channel 69 to outlets in the mould face. The plate 68 is heated by means of heating elements 75 and 76 held in place as in Fig. 3 and these are sealed from contact with the grease by means of O-rings 77.

Another embodiment is shown in Figure 5 in which the plate is heated via fluid containing channels 80 and 81. The channel 80 is located and sized to ensure proper control the temperature of grease channel 23 and face 17. Channel 81 is sized and located to ensure proper control the temperature of grease channel 20. Seals 82 are provided to prevent the escape of fluid. The channels 80 and 81 can equally be used for cooling through external valving not shown.

Another embodiment is shown in Figure 6 in which a manifold plate 35 is mounted directly on top of the mould 10. This plate includes a large primary grease channel 37 parallel to and remote from the mould face 11. A plurality of insulated restrictive flow passages 38 extend downwardly within the mould 10 from channel 37 to a

secondary channel 39 formed within the mould. A second set of restrictive flow passages 40 extend from the channel 39 to outlets in the mould face 11. These restrictive flow passages 40 are positioned accurately at a specific distance from the metal meniscus level, this distance being dependent on the fluid viscosity- temperature relationship and the temperature of the mould face. The channel 37 is sealed by means of studs 36 and O-rings 41 and 42 in corresponding channels. With the arrangement shown in Figure 6, grease is pumped into the primary channel 37 in either solid or liquid form. During casting, pressure is maintained within the channel 37 such that grease in liquified form is uniformly distributed through the passages 38, secondary channel 39 and passages 40 to the mould face 11. When solid lubricant is pumped into channel 37, the heat from the molten metal and the temperature of the mould wall serve to melt the grease.

The embodiment of Figure 7 is generally similar to that of Figure 6, but is designed to deliver the grease by gravity flow rather than pressurized flow. Thus, a modified form of delivery plate 45 is used, again with O- rings 41 and 48 in channels to provide seals. However, in this embodiment, a secondary channel 46 is left open to the atmosphere by way of vent holes 47. When this system is used, grease is pumped into channel 46 via channel 37 and flow passages 38 such that a substantially constant level of grease is contained along the length of the channel 46. When molten metal is fed into the mould, the heat of the molten metal maintains the grease in the channel 46 at a liquid temperature and this liquid grease flows from channel 46 through restrictive flow passages 40 to the surface of the mould. The vent holes 47 serve a dual purpose of permitting gravity flow from the channel 46 and also providing a visual indication as to when the channel has been uniformly filled.

A further embodiment is shown in Figure 8 in which

insulation 110 is provided on one or more surfaces of the coolant channel. This modifies the thermal profiles within the grease distribution plate in order to improve the lubricant flow uniformity and distribution on the mould face. Flow channel 38 need not be insulated in this embodiment. Incorporation of insulation in this manner may also be used if grease distribution plates as shown in Figure 3, 4 and 5 are used, in which case, the insulating layer between the distribution plate and the mould may not be required.

In yet a further embodiment which is shown in Figure 9, the grease channel 46 as described in Figure 7 is provided with an extended section 46a which, when filled with grease, provides insulation and also modifies the thermal profiles in the grease distribution channels.

An external grease recirculating system is shown in Figure 10. This includes a grease reservoir 50 having heating elements (not shown) for maintaining the grease at a predetermined elevated temperature. An outlet (suction) line 51 extends from the reservoir to the inlet of a variable positive displacement pump 52. The discharge 53 from the pump travels through either line 59 or through lines 59 and 55 simultaneously depending on the positioning of a solenoid valve 54. When the solenoid valve 54 is in closed position, hot liquified grease flows through line 59 and needle valve 60 and around a recirculating loop 61 within grease distribution plate 56. This hot liquified grease serves to heat the distribution plate 56 prior to returning to reservoir 50.

During a casting, the solenoid valve is in the open position and this means that hot liquified grease flows through both lines 59 and 55. The proportion of flow between each of these lines 55 and 59 depends upon the adjustment of the needle valve 60. The hot liquified grease flowing through line 55 continues through distribution plate 56 and out through lubricant outlets

57. During casting, the amount of heat from the hot liquified grease generated within distribution plate 56 remains unchanged since the total flow of hot liquified grease through plate 56 remains the same whether solenoid valve 54 is open or closed. With this external recirculation system, the distribution plate 56 is kept hot at all times while pump 52 is running, since the heating medium is the preheated grease from reservoir 50. If the pump 52 is stopped while solenoid valve 54 is in the closed position, the grease plate 56 cools down causing the grease to solidify. This provides the advantage of reduced spillage from the lubrication plate when the mould is tilted.

The system also includes a relief valve 62 to protect the variable positive displacement pump 52 if the needle valve 60 is accidentally closed while solenoid valve 54 is in the closed position.

The system may also include an air purge for purging the lines between casting runs and this may be connected to solenoid valve 54.

An external fluid heating and cooling system is shown in Figure 11. This includes a grease supply system and a heating/cooling fluid supply system. Grease is supplied to the channels 99 in the grease distribution plate from a grease reservoir 94 via pump 95. An inline grease filter 96 may be provided and a flow metering device 97. The flow metering device may be used as part of a feedback circuit to control the pump 95 if desired. A heated portion 98 of the grease delivery tube is optionally provided particularly in locations with low ambient temperature to maintain grease temperatures sufficient to ensure that the grease will flow under the applied pressures. A heating fluid is supplied from a reservoir 92 via a pump 93 to a heating/cooling manifold 100 in the grease distribution plate.

Valves 90 are provided in the heating fluid lines. Coolant 101 is supplied via valve 91a and removed through

discharge 102 via valve 91b. In operation valves 90 are open and valves 91a and 91b are closed and the fluid provides heat to manifold 100 to maintain the grease in channel 99 at the desired temperature. If valves 90 are closed and valves 91a and 91b are opened, coolant is supplied to the same manifold 100. This permits the grease to be rapidly cooled at the end of a cast for example, to prevent loss of excess lubricant which would otherwise occur when the mould is tilted. The heating and cooling fluids are most frequently water, and in this case, the coolant entering at 101 can be city water and it can be discharged 102 to sewer. If a non-aqueous fluid is used, an external coolant storage and pumping system (not shown) may be connected at 101 and 102. Figure 12 is a schematic plan view of a grease distribution plate 56. This uses the grease distribution channels and passages as shown in Figure 3, i.e. with a large primary grease channel 20 extending generally parallel to the edge faces of the plate 56, a secondary delivery channel 23 of smaller cross-sectional dimensions and laterally spaced from primary channel 20, a plurality of restrictive passages 21 extending across between channels 20 and 23 and a plurality of small restrictive delivery passages 24 extending from channel 23 to the mould face.

The distribution plate 56 is heated by means of the recirculating loop 61 connected to the heating/cooling fluid inlet line 59 and outlet line 58. The primary grease channel 20 is connected to inlet line 55. Another schematic plan view of a grease distribution plate is shown in Figure 13. Heating or cooling fluid enters via a manifold 86 and passing through the outer heating/cooling channel 85 countercurrent to the flow in the inner channel 84 before exiting at outlet manifold 87. This shows one of several ways in which temperature uniformity is produced by directing the fluid streams through parallel channels in more or less counter-current

manner.

The following Examples are also illustrative of the invention.

Example 1 Tests of grease delivery system of this invention were carried out in a system generally of the type shown in Figures 1 and 2 using a conventional 66 cm x 165 cm x 13 cm (26 inches x 65 inches x 5 inches) Super-Tru-Slot ^® Wagstaff Mould. A grease plate, generally of the type in Figure 5 was used to control grease distribution, and a conventional continuous lubrication plate was used to control oil flow in experiments using oil lubrication. Casting trials were carried out using AA5182 and AA3104 alloys and two different greases. One consisted of pure lard (Tenderflake ^® ) and the other contained additional mineral based additives (Borazol 904 ^® - a vegetable or animal-based grease containing mineral-based additives) . The grease was injected intermittently by means of a standard injector pump into the primary channel 20 in solid form at room temperature. There it was heated to just above the melting point of 40°C and the grease then moved through the passages 21, channel 23 and passages 24 in liquid form. The grease consumption figures are shown in Table 1 along with typical oil consumption figures obtained for the same mould design. The grease consumption figures also include the initial grease application (50 ml) which is applied to the mould before starting the cast, divided by the total cast time. The grease and in particular the Borazol 904 ^® gives significantly lower consumption figures than normal oil lubricants. This is believed to be a result of a combination of the grease plate system design and operation and the characteristics of the grease used. For this reason different consumption figures arise for the different greases, although for both greases consumption is less than oil consumption using conventional oil distribution means.

Table 1

Example 2

Studies were conducted on the gravity flow lubricant system of Figure 6 to determine the optimum distance of the lubricant outlet 40 above the meniscus of the molten metal 15. These were theoretical determinations based on flow down an inclined plane. It was determined that the mould temperature varies between the lubricant outlet and the meniscus, the temperature at any given level also being dependent on the alloy being cast. Three different alloys were tested, these being (1) Al-4.5 Mg-0.35 Mn, (2) 99.7 Al and (3) Al-1 Mg-1 Mn. The temperatures obtained at four different distances above the meniscus are shown in Table 2 below:

TABLE 2

From the above results, it has been found that mould temperature at any given level is lowest for Al-4.5 Mg- 0.35 Mn and highest for Al-1 Mg-1 Mn. The results are also shown in the graph of Figure 14 for both a high viscosity lubricant (castor oil) and a low viscosity lubricant (Tenderflake ^® Canola) , with higher consumptions being shown for the higher viscosity lubricant than for the lower viscosity lubricant.

The lubricant consumption was also measured at the four different levels above the molten metal meniscus and those results are shown in the graph of Figure, 15. These results show an increasing lubricant consumption with increasing distances above the meniscus and again higher consumptions for higher viscosity lubricants. Example 3

Tests were carried out generally with the system as described in Figure 1, 2 and 5. Pure lard grease (Tenderflake ^® ) was used in a Wagstaff STS mould 66 cm x 188 cm x 13 cm (26 inches x 74 inches x 5 inches) . The mould was initially lubricated with 50 L of grease and an ingot 394 cm (155 inches) in length was cast from alloy AA-3104 in a total casting time of 80 min. After starting the cast, grease was applied in an intermittent pulsed mode consisting 12 pulses of 84 seconds duration, separated by "off" periods of 312 seconds. Each pulse delivered 42 mL of grease. The resulting average grease discharge rate was 6.9 mL/min. This compares to grease discharge rates of at least 10 mL/min and preferably 20 mL/min required to maintain good distribution uniformity if grease is applied in a non-pulsed mode.