GRAFS SR – grinding machine for straight knives

GRAFS SR series grinding machine is designed for sharpening knives used in printing, paper, metal processing, wood and recycling industry. The knife sharpening machine model SR can be supplied in 4 different grinding lengths: 1 200 mm, 1 800 mm, 2 100 mm and 2 400 mm.

The grinder has a number of improvements to achieve high-quality sharpening for many years of use. It is equipped with a rotating electromagnetic chuck, it is also possible to attach knives using special clamps on the other side of the table. Angle from 0 to 120 degrees. Proper cooling of the sharpened surfaces is ensured by a cooling system with a tank and magnetic coolant cleaner with rotating magnetic drum – model MS or paper filter PS (as an option).

Developed in our firm the special holding adapter allows for quick and easy removal and fastening of the grinding wheel with three clamping screws.

Our trolley is equipped with the best class rolling rollers (PWTR) which ensures quiet and smooth moving.

In addition, as standard, the grinder is equipped with a slide carriage speed control system (potentiometer and inverter).

The machine is perfect for sharpening special purpose knives, where high precision grinding and rigidity are needed, e.g. guillotine knives for cutting paper. It is suitable also for chipper knivesgranulator bladesveneer knives and all knives were heavy duty operation is needed.

The machine has all necessary electrical tests and European Union DECLARATION OF CONFIRMITY, build in Poland on European components.

Easy operation down and up of the grinding motor by hand wheel
The range of parameters changed during or before operation (down feed, number of head passes),
Ability to set the grinding wheel motor in the angular range of 0-5 degrees (possibility of surface grinding),
Swiveling electromagnetic chuck / table (angular scale for magnetic chuck +/-90°), dimension according the model, polarity 20 mm, “S” pole type chuck, force 120 N/cm2. + T channel on the other side of the table for fixing knives with clamps
Changeable hardened steel strips on the guides
Possibility of manually position the head over the workpiece,
Possibility to move the carriage relative to the trolley (in the Y axis)
The possibility of grinding knives up to 360 mm high
Quick travel up and down the grinding wheel motor - for faster setting of the grinding motor and more efficient grinding wheel replacement
Grinding wheel motor with special holder / adapter with 3 screws for fast change any grinding wheel (CBN, DIA, grinding wheel with segments), diameter of the grinding wheel from 175 mm up to 250 mm,
Quiet and vibration-free special grinding head,
External tank (150 L) with pump 60L/min,
Variable smooth carriage speed 1-16 m/min,
Switch for carriage run adjustment,
Scale for measuring down feed / grinding motor position,
Professional in machine lighting, in grinding area (machinery lamp),
The ability to set the grinding wheel motor in the angular range of 0-10 degrees (possibility of surface grinding) in standard price
We provide machine operation training and material advice at our company's headquarters (it is possible to conduct full-day training for an additional fee in sharpening various types of knives),
As a manufacturer, we adapt the machine to the individual needs of the customer
Max grinding lenght
1200/1800/2100/2400 mm
Max grinding width*
200 mm
Max width of the knife (when angle of the chuck set in range 20-45 degrees)
360 mm
Type of mounting
Electromagnetic chuck 1 unit: 180 x 1200/1800/2100/2400 mm (120N/cm2, polarity 20 mm, „S” type) + Steel plate with T channel
Clearance (between chuck and troley)
120 mm
Swivel range magnet
+ / - 120 °
Grinding motor speed
1400 rpm (switched right/left)
Carriage speed
1m/min - 16m/min (smooth regulation)
Grinding motor power (depends from order)
5,5/7,5/11 kW
400 V – 50 Hz – 3 f
Weight (depends from model)
1300/1500/1700/2000 kg
Lenght x width of the machine
2200/2800/3000/3400 x 800 mm
Coolant pump efficiency
60 L/min
Coolant tank cappacity
150 L
Grinding wheel (every type: corundum, CBN, DIA, Grinding wheel with segments)
⌀ 175 - 250 mm
*The grinding width range can be increased due to the carriage advance function relative to troley.
Knife holder
An adjustable stand for mounting knives developed by us, useful when cleaning the knife after the sharpening / grinding process.
Magnetic separator (Model MS)
Designed for filtering coolant liquid from spoil magnetic
CBN Grinding wheel ⌀ 250 mm
Grinding wheel with insert made of HSS, NC10, NC11 (adapted to the customer's needs).
Diamond Grinding wheel ⌀ 200 mm
Grinding wheel for sharpening knives with carbide insert HM (adjusted to the customer's needs).
Grinding wheel with corundum segments ⌀ 250 mm
Grinding wheel for more efficient sharpening of knives, where a quick material removal is required (e.g. knives for mills, crushers, chipper knives). We adapt the grinding wheel to the customer's needs.
Specialist full-day training (STEEL SS, NC, HSS) at the customer's premises.
Training in the field of professional knife sharpening, (the price does not include travel costs).



Very easy to control the machine using the front panel.

The feed/drive speed of the carriage is set using the potentiometer knob. Simple switching on and off – the operation of the grinding wheel motor, electromagnet, trolley feed and cooling system – using switches.


GRAFS SR is equipped with the swiveling electromagnetic chuck with T channel plate on the other side of the chuck (for clamps mounting).

These two systems allows for secure fastening of the workpiece and precise grinding angle setting in the range from +-120 degrees.

The electromagnetic chuck can be produced with “S” Pole or in standard version. Chuck has polarity from 5 mm up to 25 mm (depends from order) and with max force 120N/cm2. Chuck is easily controlled from the control panel.

We help to choose the best solution for specific knives.


We provide individually tailored clamping systems for various knives.

We help to choose the most appropriate version for the convenience of our customers.

FIXING BOOK KNIVES: Attaching the knives to the paper cutters must be very precise. We have developed a special bar that keeps the knives in place. Thanks to this, each sharpening runs in a straight line and is repeatable.

The positioning bar can be easily moved up and down. Made of aluminum ensure safe operation.





FIXING CHIPPER KNIVES / RECYCLING BLADES: Attaching chipper knives or recycling blades sometimes requires mounting using special brackets. It is very important to sharpen each pair or set of knives equally. Uneven processing of material from each knife may result in improper operation of the mill or chipper. We provide a variety of solutions depending on the requirements of our clients. Even very short knives arranged in series can be precisely adjusted.


The machine is equipped with an inverter to adjust the carriage speed from 1 to 12 m/min.
All electronic components are made of high-quality materials from proven manufacturers (mainly Schneider)



The grinder has covers to prevent excessive release of coolant dust during grinding. The amount of coolant fed to the machine by pump can be freely adjusted. Collant distributor in carriage is made of inox. The whole carriage can be manually positioned over the workpiece, which prevents the abrasive wheel from accidential hitting the workpiece. Machine has fast drive of main motor up / down by stepper motor, and slow approach by hand wheel. Steering by hand wheel can be also possible during work of the machine.


Our 24V safe LED lighting makes your work visible and safe. All our SR models come standard with a professional lamp.


The machine’s grinding wheel motor is manufactured in one of the oldest polish company: CELMA Inducta. Motor is additionally reinforced by GRAFS and is equipped with special spindle bearings with the elimination of axial play. Is also equipped with a special holder / adapter for quick mounting of the grinding wheel with three clamping screws. The grinding wheel can be changed in 1 minute. In SR model motor is available in several power variants: 5.5 kW, 7.5 kW, 11 kW.

Grinding Wheel motor can be produced in option with stable RPM (1450 RPM) or with changeable RPM, smooth regulation by potentiometer and inverter in range 1000 – 2800 RPM.


Specially designed holder / adapter allows for mounting different types of grinding wheels with just three locking screws. There is posiblility of fixing: ringwheels,  segmental heads, diamond and CBN wheels  (diameter from 150 mm up to 250 mm).

We developed our carriage for as convinient grinding wheel exchange as posiible. The space needed for exchange the grinding wheel is enough for fastening even big 250 mm segmental grinding heads.

With our system of the grinding motor sledge fast drive, exchange of the grinding wheel takes around 1 minute!



Our Focus is to manufacture machines which will work many years without any mechanical interference of the owner. We provide it by well known and tested solutions:


The grinding wheel motor’s sledge are driving on specially machined bronze guides. This solution allows for efficient and long life usage. The sledges are also positioned by regulated lubricated left and right steel guide. Even after many years of working the play on sledges can be easily eliminated.


The carriage’s driving system consists of two precisely machined steel guides covered with hardened strips of appropriate hardness.

High-strength PWTR rolling rollers (mounted in a trolley) move along the strips. This solution is more durable than standard linear systems used in CNC machines.


In each of our SR models, we have the ability to easily adjust the angle of the grinding wheel motor in the range of 0-5 degrees.

When we grind knives, the motor is set to about 2 degrees, but sometimes when there is need to grind flat surfaces – it’s easy with our adjustable mechanism.


In our SR model as a standard equipment are precise scales.


In case of need to regrind wider objects it is possible to regulate position whole carriage relative the trolley.

Thanks to this function in SR model there is possibility to regrind even knives with 360 mm width.


In the SR model, we can operate the feed of the grinding wheel motor to the cutter using a handwheel or, as an additional option, we can use a mechanical feed system on the so-called ratchet.

Stemless induction limit switches are responsible for changing the direction of travel of the trolley. Emergency limit switches located closer to the center of the stroller provide additional protection.


The machining coolant filtration module developed and built in our company consists of a magnetic separator MS model, with rotating magnetic drum (for removing magnetic spoil), mobile tank of capacity 150L and coolant pump with efficiency 60L/min.

Another option is PS paper band filter, which is dedicated fol filtration non magnetic materials like dust from grinding wheel or carbides. Filter works in automatic mode. When the dirty coolant reach special level then sensor will start paper band rolling.

The combination of both filters MS+PS, gives a high level of coolant purity which translates into quality and speed of sharpening process.

It is dedicated when sharpening knives for paper cutters and three knife trimmers when carbides are regrinded.



The machine carriage can be manually positioned over the knife, which allows for secure positioning of the grinding wheel disc relative to the workpiece. Thanks to the possibility of sliding the carriage relative to the trolley in Y axis, it is also possible to sharpen / grind objects or knives of larger widths (up to 360 mm).


Constructed of welded steel plates with a thickness of 20 mm. The trolley moves on 4 PWTR rollers with a diameter of 62mm (including 1 on an adjustable eccentric) for precise adjustment of the position of the rollers in relation to the guides. Additionally, on one of the guides, 2 internal fixed rollers and 2 external adjustable rollers are used to guide the trolley evenly in relation to the base.


The machine base is made of electro welded steel sheets (10mm) with appropriate ribs, in cell design – which makes the whole structure extremely stable. The rigid structure helps to avoid any vibrations or deflections during machining. The base is available in several lengths enabling the grinding range: 1200 mm, 1800 mm, 2100 mm, 2400 mm.

As a carriage running system, there are two steel guides equipped with hardened strips of appropriate hardness. High-strength PWTR rollers move on the straps. This solution is more durable than standard linear systems used in CNC machines.