Components used for heavy lifting are totally different from the ones used in robotics applications.
You will find in our website a complete range of components dedicated to this type of handling .

The advantages of the handling by suction cups make this gripping technology the solution that should be considered first and foremost :
        Reliability
        Simplicity 
        No damage for the product 
        Gripping by only one side 
        High transfer rates
        Economical
        Quick and easy replacement 
        Gripping of different tight products: sheets, glazing, composite boards, stones, concrete … 
        Low servicing
        High accuracy positioning
        Safety

SAPELEM is very concerned regarding safety matter. Check for the following rules : 
        Safety factor
        Dynamic forces
        Handling direction : vertical or swivelling

 Working principle of a suction cup :

    Suction cup is activated by pressure difference between inside (vacuum) and outside (atmospheric). Suction cup is thus able to lift few grams to several tons in accordance with its diameter.

Units : 1 atm = 1,013 bar = 1013 mbar 1daN/cm² 101,3 kPa 760 mmhg

  
Liufting capacity

• Calculated values :

Tear-out force: F = (Patm - Pv) x S1 Lifting capacity: C max = 1,03 x ΔP x S2 Round suction cup’s lifting capacity: C max = 0,81 . ΔP x D² Calculation of suction cup’s diameter: D = 1,11 x (C/ ΔP)0,5 Example: In theory, to lift a 100 kg load, with a vacuum level of 80% D=1,11 x (100/0.8)0,5 = 12,4 cm	ABREVIATIONS F : tear-out force Pv : suction cup pressure Patm : atmospheric pressure S : useful surface P : vacuum pressure D : diameter C : theorical lifting capacity
Nota: 0,81 bar = 80% vacuum = 80 Kpa = 600 mm hg	UNITS U : % vacuum F : Newton Pv : Pascal Patm : Pascal S2 : cm2 S1 : m2 P : bar D : cm C max : kg

• True conditions:
  

    Effective suction cup lifting capacities vary significantly from the calculated value, due to :

• Product properties:
  •  Non porous
  •  Porous                            
• Surface condition:
  • Cleanliness
  • Roughness
• Useful surface of the suction cup
• Shape (dimensions) of the product
• Suction cup deformation affected by
  • Vacuum level
  • Force applied
  • Shape
  • Material

    Because of these parameters, a safety factor for vacuum handling is mandatory.
   

• Safety factor

    SAPELEM represents France at the European Committee for Standardization. The draft code EN 13155 set out by CEN/TC 147 states that:

« Vacuum lifting systems must be dimensioned so that the adherence strength is always at least equal to 2 the effective component of the nominal load at the lower limit of the vacuum pressure range which may be used (…) »

This safety factor of 2 (for horizontal handling) takes into account only a part of uncertain parameters (surface condition, etc…). The following points must be specifically considered.
   

• Materials

    Used materials have a significant effect on the lifting capacity of a suction cup. Performances related to the 4 commonly used materials are indicated on each technical data sheet (see the following section). 

• Dynamic forces

    According to the formula F = M × A (Force = Mass × Acceleration), the dynamic forces, induced by movements, must not be neglected. They must be added to the weight of the product. This criterion should be carefully considered especially in the cases of high speeds, high accelerations, quick transfers, fast turning or pivoting. Tear-out force will increase significantly.

    When used in vertical applications, a suction cup is subjected to frictional force. At the first approach, in order to take into account the friction factor, SAPELEM advises to increase the safety factor which becomes 6. The values in the force tables of the technical data sheets must therefore be divided by 3.

     For example, a suction cup rated for 12 kg in horizontal handling becomes 12/3 = 4 kg in vertical handling.

    It has the effect of increasing the size of the suction cup.

    In case of problem with the size of the suction cup, it is necessary to measure the friction factor suction cup / product handled to determine the exact minimum size of the suction cup 


  SAPELEM engineers are at your disposal to help you in this determination.

• Altitude

Higher is the altitude, lower is the atmospheric pressure. If the pressure remains the same in the suction cup, its lifting capacity decreases.

Taking all these parameters into consideration, the example on the previous page with :

• a nitrile suction cup
• a vacuum of 810 mbar max.
• a lower limit of vacuum range at 600 mbar (alarm trip threshold)
• a safety factor of K = 2 and with no acceleration

The calculation of the diameter becomes :
D = 1,11 x (KxC/u)0,5 =(2x100/0,6)0,5 = 20,3 cm (and no longer 12.4 cm)

See below for criteria to be taken into account.

 SAPELEM engineers are at your disposal to help you to determine this data.

Flexible products

    Suction cups’ quantity must be sufficient to guarantee the product flatness.

Thin or fragile products

    To prevent the suction cup to deform the product, it is better to use several smaller suction cups or suction cups with stops.

Porous products or uneven surfaces
    Porous materials induce leakage through the products. The vacuum level in the suction cup (and thus its lifting capacity) will be lower (F = k.U).
Test must be performed to confirm cups and vacuum generator determination.

 SAPELEM and its retailers’ network are at your disposal to perform them.

Vacuum level effect

The lifting capacity of a suction cup (thus the suction cups’ quantity to be used to lift a given weight) is directly proportional to the used vacuum level
    To get the lifting capacity of a suction cup, at a pressure different to the 0.8 bar indicated in the tables, use the ratio lifting capacities / vacuum level :
(C 0,6/ C 0,8 ) = (ΔP 0,6 / ΔP 0,8)

Example: if at 0.8 bar the lifting capacity of a suction cup is 12 kg, at 0.6 bar it becomes:
C 0,6=(12x(0,6/0,8) = 9 Kg 

    The horizontal lifting capacities of the suction cups are given with a safety factor of 2. For vertical handling, this result is again divided by 3.

Suction cups’ model determination

There are two types of steel vacuum pads :

• Steel vacuum pads with foam gasket
• Ventouses à joint moulé double lèvre 
   

        Steel vacuum pads with foam gasket

Functions:
    These vacuum pads allow the handling of products with uneven and no smooth surface such as: stone, concrete, bulb plate…
    The foam gasket also allows to manufacture steel vacuum pads on request, perfectly adapted to the forms of products to be handled.

Characteristics :
    Round, square, rectangular or oblong, they have a standard lifting capacity up to 2 tons per suction cups. In special application it can be several tons.
    Different types of mounting are available for horizontal or vertical handling.

There are several shapes of foam gaskets

• NM : Square gasket, Neoprene foam for standard applications
• TI : Isosceles triangle gasket, Neoprene foam, makes the gripping of very shaped or very uneven surface products easier
• SR : Square gasket, Silicone foam for applications up to continuous 200°C

        Steel vacuum pads with double lip moulded seal

Function:
    These vacuum pads allow the handling of smooth products such as: glazing, sheets, plastic composite….
Thanks to the “double lip” technology, the moulded seal offers 2 main advantages :

• Incomparable life lasting
• High tightness for safety

Characteristics :
    Round, their lifting capacity is up to 1300 Kg per suction cups.
Different types of mounting are available for horizontal or vertical handling.

        Stop

    Internal stop of suction cup has two main functions :

• On thin products: It allows the product to lean on a flat surface so that to limit the deformation and/or to avoid the breakage of fragile products
• On manipulators with high accelerations: It acts as friction pad between the part and the suction cup. It limits thus the risks of relative skidding

Functions:

Safety vacuum units have the following functions :

• Pneumatic (single-stage venturi) or electric (pumps with vanes) vacuum generation 
• Safety vacuum tank to hold the part in case of supply failure of the vacuum generator
• Vacuum piloting (hold / release of the part)
• Control by buttons box, terminal or connector to integrate the controls of the safety vacuum unit during the installation
• Sound alarm on lack of vacuum during gripping and:

                    On supply failure during gripping for pneumatic safety vacuum units

• Vacuum level visual control by vacuumeter with red and green zones

1. Vacuum generator 2. Nonreturn valve 3. Vacuumeter 4. Vacuum tank 5. Vacuum switch 6. Distributor 7. Vacuum filter

Which flow to choose ?

    The vacuum generator’s flow affects the draw off time of a given volume and the capacity to compensate leaks. It is thus advisable to make sure of the tightness and the dimensions of the vacuum circuits.

    Our current range of safety vacuum units covers a flow’s range from 3 to 40m3/h.

    By experience and to sum up please find below the table for flow determination of a vacuum unit to handle tight products with length  6 000mm

Suction cups' lifting capacity			Advised vacuum flow	Advised vacuum tank volume
Mini	Maxi		in m3/h	In litres
0 Kg	250 Kg		3	5,5
250 Kg	500 Kg		7	5,5
500 Kg	1000 Kg		7	11
1000 Kg	1500 Kg		10	11
1500 Kg	2000 KG		16	11
2000 Kg	4000 Kg		25	20
4000 Kg	et +		40	50

    For products with length > 6 000mm: outclass the flow from one rank
For rough surface or even lightly porous products, only trials with samples can allow to determine the necessary flow.

    SAPELEM engineers are at your disposal to help you in this determination.

Which energy to choose ?

SAPELEM offers you two types of vacuum generators according to the energy used :
• Pneumatic vacuum generators
• Electric vacuum generators

    For heavy handling the energy determination essentially depends on the easiness to bring the energy to the zone to be served by the lifting beam. Thus under travelling crane it is very often easier to use electric vacuum units because it is enough to take a cable down with a drum up to the hook.
    On stationary brackets it is economically interesting to use pneumatic vacuum units (no servicing of the vacuum pump….)
    In case of lack of energy on working area, SAPELEM offers you a range of low voltage safety vacuum units with self-contained small box.

Different kinds of control

• Standard buttons box

    The standard buttons box has 3 buttons for the pneumatic safety vacuum units and 4 buttons for the electric safety vacuum units. The functions of the buttons are the following :

1 On-Off light rotary holding button (only for electric safety vacuum units)
1 « part gripping » push green button (light button on the electric safety vacuum units; control light for gripping control)
2 impulse red buttons for latch off bi-manual control.

The cable in a 4.5m coating (standard one) allows the operator to pilot these operations by remote control.

• Buttons box with annexs

    The buttons box has 5 buttons for the pneumatic safety vacuum units and 6 buttons for the electric safety vacuum units. The functions of the buttons are the following:

Function of the standard buttons box + piloting of 2 additional movements (prehensile swivelling for example).

• Manual valve 3/2

    This economical option allows to manually activate the "hold / release" of the part but it is incompatible with the sound alarms in gripping. Indeed, in that case the sound alarm starts in gripping as in releasing in case of lack of vacuum or supply failure of the vacuum generator.
Besides it imposes a nearness of the operator with regard to the part.

• Manual distributor 5/2

Allows the same management of the alarms as the standard buttons box but the presence of the operator near the prehensile is mandatory.

• With no buttons box

    The controls are put on a 17 poles connector. A 4,5m coating contact cable and a 17 poles connector are supplied with the safety vacuum unit in order to allow you to connect the safety vacuum unit to your control box or to your automaton.
Warning: Standard piloting voltage 24 Vac supplied by the safety vacuum unit.

   SAPELEM engineers are at your disposal should you need other kind of control