Summary of Interpretations of NADCA B152.1 – 2006

If you have further questions that need interpretation, please fill out the Safety Standard Interpretation Form.

Clause 3.34 Injection (Definition)

Q 1.  Can a cold chamber shot cylinder be operated with a single solenoid valve, allowing it to return with loss of output power if it is protected by a guard and ladle?

A 1.  The answer to this question is addressed in 4.5.5, Power Loss, of ANSI B152.1-2000.  The phrase states in part, “de-energize all equipment that is potentially hazardous in the die casting area.”  If the ‘guard and ladle’ accomplish this then you have met the requirement.  However, it is difficult to guard all potentially hazardous areas and it is generally recommended that a double solenoid valve be used.

Clause 4.1.5

Q.1.  Is a brake or friction type device considered to be equivalent to a ratchet bar as referred to in Clause 4.1.5?

A.1.  The principle of operation of a wedge type brake or friction type device meets the intent of an “equivalent device”

CLAUSE 4.4.1

Q.5 On our operator doors we currently use (2) limit switches for an interlocking method. One at the door close position and one at the “linkage” end of the door. When the door closes it makes one switch and is required to drop off the other before initiating the die close cycle. After reading the standard it sound as if we should add a locking solenoid to hold the door shut when it is in cycle and a separate cycle start button. Is this a correct interpretation or is something else required?

A.5 A separate and locking redundant sensor is required on the operator door.

CLAUSE 4.4.4

Q.2 Should I assume that Clause 4.4.4 applies ONLY to cold chamber machines?

A.2 No.

Q.3 Clause 4.4.4 stated that injection shall not occur unless the machine is locked. Is injection forward in manual mode permitted with the machine not locked?

A.3 Yes. Injection forward is permitted in manual mode with the machine not locked provided all the requirements for manual mode are incorporated. See Clause 8.3.

Clause 4.1.1

Q.5 The standard regarding the “operator’s door”(4.1.1) does not mention a “viewing window”. Please provide a standard(s) that references materials approved for the construction of “clear” viewing windows. Are there regulated materials or recommendations to assist us in our determination?

A.5 There are no standards to cover the construction of “clear” viewing windows as applied to die casting. Currently there are no materials regulated or recommended for viewing windows. If clear materials are used to cover the viewing windows, the materials must be sufficient to withstand the heat and force of molten metal striking the window without breaking.

Clause 4.1.7

Q.1 This question concerns a method to prevent platen motion with a safety isolation valve (4-way proportional). We are proposing to insert a safety isolation valve between the clamp pilot valve and its slave valve. This isolation valve is solenoid operated directly by a limit switch on the operator door. It must be energized to allow the clamp pilot to shift its slave valve and cause platen motion. If power is off, the isolation valve returns to the safe position and the clamp slave valve to its blocking position. The isolation valve position is monitored by an interlock switch and the control system is programmed to watch for the appropriate feedback signal. If the feedback signal fails, the machine control is placed into an emergency stop condition and a “clamp” isolation valve fault” signal is displayed. Is this an acceptable method to meet the requirements of 4.1.7?

A.1 Yes. As explained, the proposed circuit meets the requirements of item #4 provided under clause E4.1.7 provided the limit switch is independent of all other interlocks

Clause 4.4.2

Q.1 Am I correct in interpreting that this clause requires that the injection unit cylinder be held back with a monitored mechanical device (such as a pin or fork) so that it cannot drift or unintentionally move forward?

A.1 Yes. Your interpretation is correct.

Q.2 Am I correct in interpreting that this clause requires that the injection cylinder, bridge gooseneck (a complete assembly) moves to and from the nozzle/sprue contact position then this entire moving assembly must have all energy removed and the assembly is to be locked into position to prevent unintentional motion?

A.2 No. Clause 4.4.2, paragraph 3 of the standard does not require that all energy is removed or that the assembly is locked into position. Paragraph 3 only deals with plunger movement not with a complete assembly movement.

Q.3 Our hot chamber machines are equipped with hydraulic blocking valves that do prevent plunger drift and are also able to stop the full force of the shot. Do we need to add this mechanical device even though our machine have the hydraulic blocking valves that provide the same safety function?

A.3 Per the standard, an interlocked and monitored mechanical device shall be used to prevent unintended movement. A hydraulic blocking valve does not meet the requirements of the standard.

A risk assessment shall be done to address the design criteria of the mechanical device per clause 7.3 of the standard.

Q.4 A LAF series Rexroth valve was installed in a hydraulic circuit to prevent unintended hot chamber plunger downward movement. It is installed directly in the hydraulic line coming out of the rod end of the shot cylinder. In order for the cylinder to move down, the fluid must flow through this blocking valve. The valve is normally closed and in its blocking position unless it is energized. The valve is solenoid controlled and energized directly from independent limit switches on the closed safety guards and the die locked position of the closing cylinder. The safety shot blocking valve is monitored with an interlock switch and the control system is programmed to watch for the appropriate feed back signal. If the feed back signal fails, the machine control is placed into an emergency stop condition and “shot block fault” signal is displayed. Is this an acceptable method to meet the requirements of 4.4.2?

We have experience with both mechanical blocking devices and hydraulic shot blocking valves and consider the hydraulic method superior. Our opinion is that the mechanical devices are prone to having more operational problems than the hydraulic safety valve method, and we’ve seen many mechanical safety devices removed or bypassed because of their problems.

A.4 No. Clause 4.4.2, paragraph 3 specifically states that a ‘mechanical device’ is to be used to prevent plunger drift.

Clause 4.1.3

Q.1 All of our limit switches report directly to our PLC. Is this an acceptable procedure or do we need separate electrical interlocking devices for redundancy?

A.1 All limit switches can be interfaced to a PLC with the exception of switches that are used for emergency stop purposes. See NFPA 79 for wiring instructions and specifications.

Clause 4.6.3

Q.1 What are the “applicable industry standards” that hoses shall be restrained in accordance with?

A.1 Refer to the complete body of specifications promulgated by the Compressed Gases Association (CGA). They have a comprehensive website. The committee has not identified any applicable ANSI Standard that addresses the question.

Clause 1.4

Q.1 In the opinion of the Safety Committee could IMA machines be excluded from ANSI/NADCA B152.1 under clause 4.1? As a precedent, ANSI standard B11.1 “Mechanical Power Presses” excluded “eyelet machines” which are very small mechanical power presses that have an inherently lower risk of severe injury because of their small size.

A.1 It is not the committee’s place to provide an evaluation of whether a particular machine complies, or does not comply with the standard. The committee will only provide interpretations or clarifications regarding the content or the intent of the standard. If hazards as indicated in clause 4.1 exist, then they should be safe guarded.

Clause 1.5.2 & 1.5.3

Q.1 Is the addition of a metal delivery system (or other ancillary piece of equipment) to a die casting machine considered a modification as referred too in clause 1.5.2 or is it considered a system integration as referred too in clause 1.5.3?

Is the addition of a metal delivery system electrical interface only (or other ancillary equipment interfaces) considered a modification as referred too in clause 1.5.2 or is it considered a system integration as referred too in clause 1.5.3?

When adding a metal delivery system (or other ancillary piece of equipment) to an old die casting machine that does not currently meet the requirements of ANSI/NADCA B152.1-2000 what portions of clause 4 are applicable and/or what portions of clause 6 are applicable?

In other words, when adding ancillary equipment to a machine is the person adding the ancillary equipment responsible for updating portions of the machine that do not comply with the current NASI/NADCA B152.1-2000 standard and will the answer to this question change after April 25, 2004.

A.1 No. It is the employer’s responsibility. Reference Clause 1.5.3 of the standard.

Clause 3.4.0

Q.1 If only a portion of a die cast machine is rebuilt or remanufactured is it required by the rebuilding company to also upgrade the machine and make it compliant wit the new safety standards? Our company does many “partial” rebuilds and we would like to offer the machine safety upgrade as an option whenever we are quoting this type of work. When we are quoting a complete rebuild or remanufactured die cast machine we include the safety upgrade as part of our standard work. We would like to know if our position is acceptable.

A.1 This question references clause 3.4.0. This is the wrong clause. The clause should be 1.5.2. The response to the question is: “No”. All parts being rebuilt or remanufactured must be in compliance with clause 4.

“General Questions pertaining to B152.1”

Q.5 The intent was all machines manufactured AND installed must comply? For example, a press that is shipped from a warehouse must be upgraded or not?

A.5 Yes. The machine must meet the requirements of the standard.

Q.6 Is the term “repair” synonymous with modification?

A.5 No. A repair is to fix or replace a defective component. A repair is not a modification.

Clause 5.2

Q.1 Is it permissible to open and close the die in manual mode with the operator’s gate open for the purpose of setting a die using two-hand control?

A.1 Yes. Provided manual mode is at a reduced speed as defined by Clause 4.7. The two-hand control requirement of manual mode protects the die setter only. All other individuals present must be clear of the die area during the opening and closing of the die.